• TABLE OF CONTENTS
HIDE
 Title Page
 Report documentation page
 Preface
 Table of Contents
 List of Figures
 List of Tables
 Introduction
 Field data collection
 Fixed bed model descriptions
 Model tests on structural...
 Summary and recommendations
 References
 Appendices
 Appendix A: Wave statistics, Vero...
 Appendix B: Test results for alternatives...






Group Title: Sebastian Inlet physical model studies
Title: Part I Fixed bed model
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Permanent Link: http://ufdc.ufl.edu/UF00078559/00001
 Material Information
Title: Part I Fixed bed model
Series Title: Sebastian Inlet physical model studies
Alternate Title: UFL/COEL (University of Florida. Coastal and Oceanographic Engineering Laboratory) ; 91/001
Physical Description: Serial
Language: English
Creator: Wang, Hsiang
Publisher: Coastal and Oceanographic Engineering Department, University of Florida
Publication Date: 1991
 Subjects
Subject: Sebastian Inlet (Fla)
lorida.   ( lcsh )
Spatial Coverage: North America -- United States of America -- Florida -- Sebastian Inlet (Fla)
 Notes
Funding: This publication is being made available as part of the report series written by the faculty, staff, and students of the Coastal and Oceanographic Program of the Department of Civil and Coastal Engineering.
 Record Information
Bibliographic ID: UF00078559
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved, Board of Trustees of the University of Florida

Table of Contents
    Title Page
        Title Page
    Report documentation page
        Unnumbered ( 2 )
    Preface
        Preface
    Table of Contents
        Page i
        Page ii
    List of Figures
        Page iii
        Page iv
        Page v
    List of Tables
        Page vi
    Introduction
        Page 1
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
    Field data collection
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        Page 9
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
        Page 24
        Page 25
    Fixed bed model descriptions
        Page 26
        Page 27
        Page 28
        Page 29
        Page 30
        Page 31
        Page 32
        Page 33
        Page 34
        Page 35
        Page 36
        Page 37
        Page 38
        Page 39
        Page 40
        Page 41
        Page 42
    Model tests on structural improvement
        Page 43
        Page 44
        Page 45
        Page 46
        Page 47
        Page 48
        Page 49
        Page 50
        Page 51
        Page 52
        Page 53
        Page 54
        Page 55
        Page 56
        Page 57
        Page 58
        Page 59
        Page 60
        Page 61
        Page 62
        Page 63
    Summary and recommendations
        Page 64
        Page 65
        Page 66
        Page 67
        Page 68
        Page 69
        Page 70
        Page 63
    References
        Page 70
    Appendices
        A
    Appendix A: Wave statistics, Vero Beach (87,88,89)
        A-1
    Appendix B: Test results for alternatives 0, 1,4 and 5
        B-1
        B-2
        B-3
        B-4
        B-5
        B-6
        B-7
        B-8
        B-9
        B-10
        B-11
        B-12
        B-13
        B-14
        B-15
        B-16
        B-17
        B-18
        B-19
        B-20
        B-21
        B-22
        B-23
        B-24
        B-25
        B-26
        B-27
        B-28
        B-29
        B-30
        B-31
        B-32
        B-33
        B-34
        B-35
        B-36
        B-37
        B-38
        B-39
        B-40
        B-41
        B-42
        B-43
        B-44
        B-45
        B-46
        B-47
        B-48
        B-49
        B-50
        B-51
        B-52
        B-53
Full Text



UFL/COEL-91/Oo1


Sebastian Inlet Physical Model Studies
Part I Fixed Bed Model







by

Hsiang Wang
Lihwa Lin
Husui Zhong
Gang Miao


January, 1991




Submitted to:

Sebastian Inlet District Commission
Sebastian Inlet, Florida.







REPORT DOCUMENTATION PAGE
I. Report No. 2. 3. Recipient' Accession No.


4. Title and Subtitle 3. Report Date
SEBASTIAN INLET PHYSICAL MODEL STUDIES January 15, 1991
Part I -- Fixed Bed Model 6.

7. Author(s) 8. Performing Organization Report No.
Hsiang Wang, Lihwa Lin, Husui Zhong, Gang Miao UFL/COEL-91/001

9. Performing Organizatioo wam and Address 10. Project/Task/Work Unit No.
Coastal and Oceanographic Engineering Department
University of Florida
iveriy of Floida Contract or Grant No.
336 Well Hall
Gainesville, FL 32611 13. of
13. Type of Report
12. Sponsoring Organization ame and Address
Sebastian Inlet District Commission Final Report
Sebastian Inlet Tax District Office
134 Fifth Avenue
Suite 103, Indialantic, FL 32903-3164 14.
15. Supplementary Notes



16. Abstract

An undistorted scale fixed bed model study was conducted by the Coastal
and Oceanographic Engineering Department, University of Florida, to investigate
the inlet and jetty improvements from six proposed structural alternatives.
The six structural alternatives are: (1) Existing jetty configuration with the
bathymetric map surveyed in 1989 for the model study, (2) North jetty extended
250 ft with a radius of about 900 ft, (3) North jetty extended 250 ft plus 100
ft south jetty extension, (4) North and south jetties extended by 250 and 100 ft,
respectively, plus 50 ft spur jetty on the north jetty, (5) North jetty extended
500 ft and south jetty extended 100 ft, and (6) Existing jetty plus partial
removal of ebb shoal.

For each alternative, a combination of current/wave conditions were tested.
A total of 88 cases were tested. The calibration of model was based on the
current strength and pattern measured in the field. For navigational improvement,
the alternative of 250 ft extension of north jetty appears to be the most
sensible among the six alternatives tested. It is, however, premature to conclude
that this alternative is the optimum configuration. More answers could be.obtained
till the completion of the movable bed model experiments, which will be the next
phase study and the results will be summarized in the Part II model study report.


17. Originator's Key Words 18. Availability Statement
Modal calibration
Structral alternatives
Wave amplification


19. U. S. Security Classif. of the Report 20. U. S. Security Classif. of Thi Pge 21. No. of Pages 22. Price

Unclassified I Unclassified 134













PREFACE


This report presents results of the experiments of six structural alternatives to
the Sebastian Inlet from a fixed bed model. It is intended to find solutions for,
improvement of boating safety and protection of beaches adjacent to the inlet. The
research in this report was authorized by the Sebastian Inlet District Commission of
September 15, 1989. The University of Florida was notified to proceed on November
14, 1989. The study and report were prepared by the Department of Coastal and
Oceanographic Engineering, University of Florida. Coastal Technology Corporation
was the technical monitor representing the Sebastian Inlet District.

Special appreciation is due to Dr. Paul Lin of Coastal Tech. for his continuous
technical assistance. Other personnel at Coastal Tech. and Inlet District Office
including Mr. Michael Walther, Ms. Kathy FitzPatrick and Mr. Raymond K. LeR-
oux also provided their support at various stages of the experiment. Appreciation is
also due to Mr. B. Hwang and Mr. J. Lee, both graduate assistants in the Coastal
Engineering Department, University of Florida, for their participation in laboratory
and field experiments.










Contents


1 Introduction

1.1 Authorization ..........

1.2 Purpose .............

1.3 Background ..........

1.4 Scope ..............


2 Field Data Collection

2.1 Instrument Deployment .

2.2 Current Measurements . .

2.3 Topographies and Hydrographs

2.4 Results ..............


3 Fixed Bed Model Descriptions

3.1 Test Facility ................................

3.2 M odel Scale ................................

3.3 Model Construction ...........................

3.4 Instrumentation ..............................

3.5 M odel Calibration ............................


4 Model Tests on Structural Improvement

4.1 Test Procedures ..............................

4.2 Test Results ................................

4.2.1 Alternative "0" .........................


i


1

. 1

. 1

. 1

. 6


9

. . 11

. . 11

. 13

....... 17


j










4.2.2


4.2.3


4.2.4


4.2.5


4.2.6


Alternative "1"


Alternative "2"


Alternative "3"


Alternative "4"


Alternative "5"


5 Summary and Recommendations


5.1 The M odel Tests ..........................


5.2 The Findings ........... ... .. .................


5.3 Recommendations .........................



References


Appendices


A Wave Statistics, Vero Beach (87, 88, 89)



B Test Results for Alternatives 0, 1, 4 and 5


.........................


.........................


.........................


.........................


.........................









List of Figures


1 Location of Sebastian Inlet, FL., and the watershed of Indian River
Lagoon. . . . . . . . . 2

2 Navigation guides under the A1A bridge. . . . 4

3 1970 jetty extensions at the inlet. . . . .. ... 5

4 Jetty extensions and shoreline changes since 1881. . . 5

5 1990 photography of South Jetty. . . . . . 6

6 1990 photography of North Jetty. . . . ... . 7

7 Aerial Photography of the Sebastian Inlet. . . . 8

8 Six alternative structural configurations. . . . ... 10

9 Locations of PUV and tide gages ..................... 12

10 Locations of referenced sea and land markers. . . .... 14

11 Bathymetric survey maps for years 1987, 1988 and 1989. ...... 15

12 Three-dimensional plot of inlet topography. . . .... 16

13 Three-dimensional plot of entire study area. . . ... 16

14 Basic wave statistics at Sebastian Inlet offshore station. ...... 18

15 Basic wave statistics at Vero Beach offshore station. . ... 19

16 Sebastian Inlet tide history; Jan.8-Feb.9, 1990. . . ... 21

17 Current and tide data collected at the offshore station. . ... 22

18 Current and tide histories at A1A bridge station. . . .... 23

19 Mean current measurement at the cross section under A1A bridge. 24

20 Current and discharge histories at A1A bridge station. . ... 25









21 Time and duration for drogue test studies. . . .... 27

22 Offshore wave history; Jan.10-11, 1990. . . . ... 28

23 Offshore wave history; Jan.30-31, 1990. . . . ... 29

24 Wave approaching direction during the drogue test studies . 30

25 Ebb current vectors droguee test by aerial photos), Jan.10, 1990. .. 31

26 Ebb current vectors (by aerial photos), Jan.ll, 1990. . ... 32

27 Flood current vectors droguee test by land transits), Jan.30-31, 1990. 33

28 Composite current vectors (by aerial photos), Jan.30-31, 1990. 34

29 Schematic map of the fixed-bed model. . . . .... 36

30 Construction of the fixed-bed model. . . . ... 39

31 Completion of the fixed-bed model. . . . .... 40

32 Photography showing grid system on the model floor. . ... 41

33 Waves and current measurement stations. . . .... 45

34 Computer simulation of wave field during ebb. . . ... 47

35 Waves generated during the ebb cycle in the model. . ... 48

36 Regions of different wave characteristics. . . . ... 49

37 Ebb current patterns measured in the field and laboratory. . 53

38 Flood current patterns measured in the field and laboratory. . 54

39 Comparison of Structure "1" and "0" ebb current vectors measured
in the laboratory. ................. ......... .. 57

40 Structure "1" flood current vectors under the northeast storm waves. 58

41 Structure "4" flood current vector field under the northeast storm
waves. . . . .. . . . . 61








42 Structure "4" ebb current vector field under the east storm waves. .62

43 Comparison of Structure "5" and "0" flood current vectors (calm
sea) measured in the laboratory. . . . ..... 64

44 Comparison of Structure "5" and "0" ebb current vectors (calm sea)
measured in the laboratory........................ .65

45 Comparison of Structure "5" and "0" flood current vectors (under
storm waves) measured in the laboratory. . . . ... 66

46 Comparison of Structure "5" and "0" ebb current vectors (under
storm waves) measured in the laboratory. . . . ... 67








List of Tables


1 Summary of jetty and inlet improvements. . . . 3

2 Field Drogue Test From Aerial Photos (Jan.10-11,1990). ...... 35

3 Field Drogue Test From Aerial Photos (Jan.30-31,1990). ...... 37

4 Vp, Qp and AVy measured in the field. ................. 42

5 Errors of water level differences in the model. . . .... 42

6 Test conditions for the six structural alternatives. . . .... 44

7 Wave Height Amplification [Alternative Ho/Referenced HD]. . 51

8 Wave Height Ratio [Alternative "1" (Hi)/Alternative (Ho)]. .... 55

9 Wave Height Ratios of [Alternative "4" (H4)/Alternative "0" (Ho)]. 59

10 Wave Height Ratios of [Alternative "5" (H5)/Alternative "0" (Ho)]. 63








Sebastian Inlet Physical Model Studies
Part I Fixed Bed Model



1 Introduction


1.1 Authorization

This study and report were authorized by the Sebastian Inlet District Commis-
sion of September 15, 1989. On November 14, 1989, the "University of Florida" was
notified to proceed. This report was prepared by the Department of Coastal and
Oceanographic Engineering, University of Florida. Coastal Technology Corporation
was the technical monitor representing the Sebastian Inlet District.

On May 23, 1919, the original legislation establishing the Sebastian Inlet District
(District) was passed by the State of Florida. In 1927 the Florida Legislature passed
Chapter 12259, Laws of Florida, which amend the original governing legislation of
the District. Chapter 12259 prescribes that "It shall be the duty of said Board of
Commissioners of Sebastian Inlet District to construct, improve, widen or deepen,
and maintain an inlet between the Indian River and the Atlantic Ocean..." (1).


1.2 Purpose

The purpose of this study is to seek navigation improvement for Sebastian Inlet.
This Part I report summarizes the results of a fixed bed physical model investigation.


1.3 Background

Sebastian Inlet is located at the Brevard/Indian River County line approximately
45 miles south of Port Canaveral entrance and 23 miles north of Fort Pierce Inlet.
It is a man-made cut connecting the Atlantic Ocean to the Indian River Lagoon
(Figure 1). Its coordinates are as follows:


Latitude Longitude
270 51' 35" N 800 26' 45" W


























V~ LUSIA --










( CANAVERAL INLET
Cocoa Ae.Ch


WATERSHED OF THE
INDIAN RIVER LAGOON
(from New Smyrna to EBASTIAN
Stuart) /SBINLET

TI NLETC

I


iST. LUCIE



0 10 20 30
MARTIN






Figure 1: Location of Sebastian Inlet, FL., and the watershed of Indian River
Lagoon.










Table 1: Summary of jetty and inlet improvements.


Date Jetty and Inlet Improvement Amount Dredged(yd3)
1886 Opening of 100 ft wide and 4-5 ft deep 66,000 sand
1924 channel; small rock jetties constructed. 500 rock
1927 Rock blasting from channel, south jetty
1929 raised; jetties extended landwards.
1931 A channel dredged to within 800 ft of the 72,000 sand
1939 ocean; pile dike near south bank built
1947 Channel dredged to 1,650 ft long, 160 ft 412,000 sand
1950 wide, 8 ft deep; jetty back fill. 11,311 rock
1951 Maintenance dredging; rubble mound north 198,000 sand
1959 jetty built; jetties extended landwards.
1962 Channel dredged to over 10 ft deep near 362,400 sand
1970* inlet entrance; inlet-south beach nourished.
1971 Dredging of a 37 acre sand trap; dredged 425,000 sand
1972t material placed south of the inlet.
1976 Maintenance dredging; nourishment of beach
1990 south of the inlet. 1,100,000 sand
* Small dredging operations also were carried out; the dredged material was estimated in
the order of 10,000-20,000 yd3.
t Sand trapped between June, 1972 and December, 1973 was estimated to be 110,000 yd3.

The First attempt to cut a man-made inlet in the Sebastian area was made in
1886 (2). In the ensuing 60 years or so, the inlet closed, re-opened and shifted a
number of times. The present configuration was maintained after a major dredging
operation in 1947-48 to open a new channel. Since 1948, a series of dredging opera-
tions and jetty improvements have kept the inlet open in this existing configuration.
Table 1 chronicles the major improvements at the inlet.

In 1962, a channel of 11 ft deep was excavated. In 1965, the A1A bridge across
the inlet was completed (State Project Number 88070-3501). Navigation guides
were installed in the open section as shown in Figure 2. The bridge forms a natural
throat of the inlet.

East of the bridge the dredged channel width was 200 ft and west of the bridge
the width was 150 ft. In 1970, the north and south jetties were extended to their
present configuration as shown in Figure 3, based on the results of a model study by
the Department of Coastal and Oceanographic Engineering, University of Florida.
The sequence of jetty structure improvement is shown in Figure 4. The present
south jetty is a sand-tight rubble mound structure as shown in Figure 5. The north
































Figure 2: Navigation guides under the A1A bridge.


jetty, on the other hand, is of composite nature; the original section completed
before 1955 is rubble mound but the extension in 1970 with total length of 452
ft is a pier structure supported by concrete pilings. The rubble mound base only
extends to water level (Figure 6).

The channel has a rocky bottom of marine origin. The cross section in the vicin-
ity of the throat is about one-half that which would result in a stable inlet with
sandy bottom. In other words, the tidal prism is about twice the value correspond-
ing to the cross section. This has resulted in rather strong currents through the
inlet, over 8 ft/sec during both flood and ebb. So far, the channel remains open
with minimal maintenance dredging. Shoals were, however, gradually forming on
both sides along the banks of the inlet. The navigation channel becomes narrower
as a consequence. The ebb shoal from the south is also slowly encroaching into
the inlet creating a cross shoal near the mouth. This shoal enhances the incoming
waves and causes them to break. These combined effects have created a hazardous
condition for small craft in the vicinity of the inlet entrance.

In 1987, Coastal Technology carried out a "Comprehensive Management Plan"
study for the Sebastian Inlet District Commission (3). In which, various engineer-
ing alternatives for maintenance and improvement of inlet navigation and beach









)NCRETE WALL


SE8aSr/4 NORTH JETTY


SCALE : 0'


SOUTH
S > < 0 SOUTH


JETTY


Figure 3: 1970 jetty extensions at the inlet.


ATLANTIC OCEAN


0 500'
Scale in Feet


OLD JETTIES (1924)
JETTY EXTENSION(1955)
RIPRAP (1959,1972)
JETTY EXTENSIONS (1970)


Figure 4: Jetty extensions and shoreline changes since 1881.







































Figure 5: 1990 photography of South Jetty.


preservation were presented. The present study is to evaluate these alternatives
through physical modelling.



1.4 Scope


The general purpose of this study is to conduct physical model investigation for
inlet navigation improvement and sand transfer schemes; the former is a fixed-bed
model study and the latter a movable bed model study. The results of the fixed
bed model testing are given in this Part I Report.

The physical model was conducted in the three dimensional wave basin at the
Coastal and Oceanographic Engineering Laboratory, University of Florida. Area
of studies covered approximately 2,000 ft of shoreline on either side of the inlet
entrance, landward of the 30 ft offshore depth contour to the A1A bridge (Figure 7).


Six alternative structural configurations at inlet entrance, as provided by the
Coastal Technology, were tested against various wave and tide conditions to de-
termine the optimum solution to improve inlet navigation. These six structural


-~ : (



i
"r---


C( 1


































r- L.l
'I...-.I --.r .:~~-..?"-
I-*-~ .r .., ,~
~. .. -c- .
;- .. ~ .
r.. 1 z

I
'
-~-
''"
~
.~~.'
., r., I-i
-ig:5 I .::.; ;1;~~~2~
.T; I.~::C .?.. rl
a:. ;"
_r*=?~; .J:~:x_~!


Figure 6: 1990 photography of North Jetty.


rrca~~ ~ ~ -r ~ .*.'
.it--. 'r 3 -
























Is. %-t
~n .''a;~F~-~a'~ Pm..I
slob."
.3L; 1~17Ca.


'' ". + '. .

(q- .'*


oo *** *, ", 4 *- *4b:
00ial Photography of the Sebastian Inlet




















Figure 7: Aerial Photography of the Sebastian Inlet.








alternatives (Figure 8) each was assigned by a number between 0 and 5 in this
report are:


0 Existing jetty configuration.

1 North jetty extended 250 ft with a radius of approximately 900 ft.

2 Plan 1 plus south jetty extended by 100 ft.

3 Plan 1 plus 50 ft spur jetty.

4 North jetty extended 500 ft plus south jetty extended 100 ft.

5 Existing jetty plus partial removal of ebb shoal.


Prior to laboratory modeling test, field data collections of wave, tide and current
were carried out for model verification and calibration purposes.

Numerical model was also used to supplement the physical model test.



2 Field Data Collection


Field data were collected during the month of January, 1990 at the Sebastian
Inlet. The purpose of the field work is to establish baseline information to be used as
input boundary conditions in the physical model. They are also used for calibration
and verification purposes for both the numerical and physical models.

Field data collected included:


(a) Tidal information at fixed points.

(b) Directional wave information at offshore boundary.

(c) Current information at fixed points.

(d) Drogues tracking at flood and ebb tidal cycles.

(e) Current measurements at cross section under A1A bridge.















TYPE: "1"
-30'--


TYPE:"3"

-30


Figure 8: Six alternative structural configurations.


TYPE:"0"
-30,


TYPE :"2"

-30'








2.1 Instrument Deployment


On the 9th and 10th of January, instruments were deployed as shown in Fig-
ure 9. In the offshore location just outside the 30 ft contour, a self-contained PUV
directional wave gage, as manufactured by the Sea Data Inc., was deployed near the
bottom. This gage provides directional wave information, water surface elevation as
well as current information. The gage began collecting data at 12:00 pm, Eastern
Standard Time, on the 9th of January, 1990. Current and wave data were collected
(every 3 hours) at a sampling rate of 1 Hz for 17 minutes. Tidal information was
obtained by measuring the water surface elevation through bottom pressure gage.
This information was also obtained at every 3-hour interval by averaging 17-minute
data.

Under the bridge, a PUV gage similar to that of the Sea Data instrument, but
assembled by the COE Laboratory, was installed approximately one feet from the
bottom. The gage was strapped on one of the vertical piles of the navigation guide
on the south side of the channel. To minimize the wake effect created by the leading
pile, the gage was mounted on an arm, 3 ft long and into the navigation channel.
Data were taken at every 15-minute intervals. Water surface changes and mean
current were obtained by averaging one minute data sampled at 1 Hz (60 data
points). Waves were not analyzed because their small values.

Inside the channel, on the south side, a continuous-recording tide gage was
installed on the Henry's Dock.

The offshore gage and the gage under the bridge were retrieved on February 1.
The tide gage at Henry's Dock remained in operation until February the 9th.


2.2 Current Measurements


The current pattern in the offshore region including the outer region of the inlet
is very complicated. With the limited budget and time constraint, it would not be
feasible to obtain meaningful current information by stationary single point mea-
surement as too many current meters would be required. Therefore, it was decided
to map synoptic current pattern by tracking drogues. This task was accomplished
by aerial photographs from a low-flying aircraft at 1,000 ft. The drogues were cross-
vanes of 1 ft deep tied to a flat styrofoam float of 2 ft x 2 ft square. The distance
from the vane to the water surface is adjustable. In this study, the depth of the
vane was fixed to 2 ft. A series of six markers were placed on the beach face. In the
offshore region, a series of six marker buoys where also deployed. These markers
were used to fix the drogue position by triangulation. Figure 10 shows the positions






















































Figure 9: Locations of PUV and tide gages.








of these markers.


Two measurements were carried out. The first one was during the period of
January 10th and 11th in the ebb cycle. A total of 9 runs were conducted: each run
covered a period of 15 to 45 minutes depending upon the current strength. Within
each run, airplane looped around the area in every 2-5 minutes. Two boats were
employed to support the operation which entailed picking and dropping drogues,
moving sea markers and identifying drogues when needed. The second measure-
ments were made in January 30th and 31st during the flood and ebb cycles. A total
of 5 runs were performed. In this measurement, the operation was hampered by fog
in both days. In the second day, the exercise had to be cut short when a thunder
head appeared. To compensate for the lost time, drogues were tracked by transits
from the land. Because the strong current condition, the number of drogues can
be adequately tracked were limited to not more than three while the airplane can
track up to 7 or 8 drogues at once.

In addition to the synoptic drogue tracking, currents were measured at the
cross section under the bridge from a boat transiting the channel. An impeller-
type duct current meter was used. The purpose of this measurement is to establish
the discharge at this control section which is the input boundary control in the
physical model tests. The data also serves to check the current measurement of the
stationary gage under the bridge.


2.3 Topographies and Hydrographs


No hydrographic survey was conducted under the present study. Hydrographic
survey maps were provided by the Coastal Technology Corporation for years 1987,
88 and 89. These surveys were conducted by Morgan and Eklund Inc. of Deerfield
Beach, FL. They were reproduced in Figure 11. On the north side of the inlet, the
contours are rather smooth. On the south side, a substantial ebb shoal has been
developed over the years. A scouring hole on the north end near the inlet entrance is
evident. A flat 10 ft-deep marginal flood channel runs parallel to the shoreline just
outside the south jetty. Between the scouring hole and the marginal flood channel,
the ebb shoal appears to extend into the inlet, forming an oblique shoal from south
to north jetties. The main channel inside the inlet, as reported by divers, has an
uneven rocky bottom. These features are shown in Figure 12. A prospective view
for the entire area is given in Figure 13, which shows the extent of the ebb shoal
region.

By comparing these hydrographic surveys, one sees that the north side is rather
stable but the south side is rather active. The ebb shoal and the scouring hole







































3600


3300
I-
LL
3000

CD
S 2700

O
3o 2400
SED SEA BUOY MARKERS

C 2100 -
LL-
Lj 1800 -
z
CC 1500
--
O
- 1200


a: 900
0
Cv 600 -
I I
U-
C0 .. .. .. ... ........................................
LL

S 0 I k LAND MARKER; I


-2100 -1800 -1500 -1200 -900 -600 -300 0 300 600 900 1200 1500 1800 2100

LONGSHORE DISTANCE FROM S. JETTY (FT)





Figure 10: Locations of referenced sea and land markers.




14













DEPTH CONTOUR IN FEET


1987


1.00 0.00


8.00


1988


16.00 24.00 32.00 10.00 8l.00 s5.00
X (FT) x100


S3S
35


1.00 0.00


8.00


1989


I1.oo 24.00 32.00 4b.00 1.00o 55.00
X (FT) OO00


-8.00 0.00 8.00 16.00o 2.00o 32.00 ub.oo e4.oo 56.00
X (FT) x100

Figure 11: Bathymetric survey maps for years 1987, 1988 and 1989.


mi


I '


mi
















Shoreline


0 100 200 It.
I -I--_-_-L N


Figure 12: Three-dimensional plot of inlet topography.


Figure 13: Three-dimensional plot of entire study area.








alternatives (Figure 8) each was assigned by a number between 0 and 5 in this
report are:


0 Existing jetty configuration.

1 North jetty extended 250 ft with a radius of approximately 900 ft.

2 Plan 1 plus south jetty extended by 100 ft.

3 Plan 1 plus 50 ft spur jetty.

4 North jetty extended 500 ft plus south jetty extended 100 ft.

5 Existing jetty plus partial removal of ebb shoal.


Prior to laboratory modeling test, field data collections of wave, tide and current
were carried out for model verification and calibration purposes.

Numerical model was also used to supplement the physical model test.



2 Field Data Collection


Field data were collected during the month of January, 1990 at the Sebastian
Inlet. The purpose of the field work is to establish baseline information to be used as
input boundary conditions in the physical model. They are also used for calibration
and verification purposes for both the numerical and physical models.

Field data collected included:


(a) Tidal information at fixed points.

(b) Directional wave information at offshore boundary.

(c) Current information at fixed points.

(d) Drogues tracking at flood and ebb tidal cycles.

(e) Current measurements at cross section under A1A bridge.









appeared to change from year to year.


2.4 Results


Field data collected at Sebastian Inlet were analyzed using the standard data
analysis software developed by the Coastal and Oceanographic Engineering Depart-
ment. A brief summary was given here. Detailed data including final form for the
measured waves, currents and tides are available in 5.25" floppy diskettes at the
Department of Coastal and Oceanographic Engineering, University of Florida.

Waves

Figure 14 shows the basic wave statistics, including the modal period TM, sig-
nificant wave height H,, dominant wave direction (to) 0, and directional spreading
parameter S, at the offshore station. The spreading parameter is governed by the
directional distribution of the waves; a unidirectional sea will have large values for
the spreading parameter, while a very "confused" sea will have low values for the
spreading parameter. The wave condition is very consistent with the waves regis-
tered off Vero Beach (see Figure 15). Therefore, the long term wave data collected
at Vero Beach by the Department of Coastal and Oceanographic Engineering can
be used with confidence for the Sebastian Project. The annual wave statistics at
Vero Beach for the years of 1987, 1988 and 1989 were given in Appendix 1.

In the month the data were collected, waves were moderate and predominantly
from the east. High waves were generally from north east. During the 22 days of
recording, the high waves occurred in the following periods:

Time (hr) Max. Hs (ft) Direction (from)
Jan. 13-14 4.65 N
Jan. 16-17 4.56 NEE
Jan. 26-27 4.80 NNE


The corresponding maximum significant wave height during the same periods
at Vero Beach were 4.7, 4.8 and 4.75 ft, respectively. This clearly illustrates the
consistency of these two stations. Examining the Vero Beach wave data, the ex-
treme waves during the three-year span (87-89) were in the order of 6.5-7.5 ft with
corresponding period of about 8 seconds.

Tides

The tide is semidiurnal in the Atlantic. The tidal curves at the three recording









SEBASTIRN INLET


COE LAB, UF


20


15

TM 10
(SEC)
5

0


6




Hs 3
(FT)



0




N

9 E

S




120

90

S 60


30

0


1 5 10 15 20 25 30



(C) DOMINANT WAVE DIRECTION







1 , I ~m .llM.4

1 5 10 15 20 25 30

JAN.,1990


Figure 14: Basic wave statistics at Sebastian Inlet offshore station.


1 5 10 15 20 25 30














VERO BERCH P ONLY


COE LAB. UF


20

15

Tm 10
(SEC)
5

0


1 5 10 15 20 25 30


JANUARY. 1990


Hs
(FT)


JANUARY, 1990


1 5 10 15 20 25 30

JANUARY, 1990



Figure 15: Basic wave statistics at Vero Beach offshore station.


(B) SIGNIFICANT WAV HEIGHT







SI I I I I I I I I I I I i I I I I i i I I I I I I I I








stations are shown in Figure 16. The range of spring tide is about 5 ft in the
offshore region and reduces to about 3 ft at the A1A Bridge. At the Henry's Dock
it is further reduced to less than 1.5 ft. There is no noticeable phase lag at the
three locations. The information of tidal elevation is important in the model study
as the control at the boundaries is largely determined by the water level.

Currents

At the offshore station, a persistent northward current was recorded, with a
magnitude fluctuates from 1.3 to 1.7 ft/sec. This is an unusually high current for
the offshore region. Instrument malfunction was suspected at first. The current me-
ter was reexamined in the laboratory and was found to function properly. Divers
at the site also stated that they have experienced high bottom current. Therefore,
although the origin of this steady current could not be readily identified or inde-
pendently verified, its presence seems to be real. Figure 17 shows the time series of
tidal elevation and near-bottom current at the offshore station.

Figure 18 shows the time series of tidal elevation and tidal current under the
A1A bridge. The positive current is pointing towards the bay (flood). The flood
current is usually higher than the ebb current. Maximum current during this period
reached 6-6.5 ft/sec. The tidal current is seen to be in phase with the tidal elevation.

Mean current at the cross section under the A1A bridge was measured by
impeller-type duct current meter in January 30-31, 1990 during the ebb tidal pe-
riod. The purpose of this measurement was to establish the discharge and to corre-
late this discharge with the fixed-point current measurement. Figure 19 shows the
cross-sectional mean current measurement. The current was reasonably even across
the section. Based upon the established correlation, the estimated discharge along
with the current during the measurement period is plotted in Figure 20 at the A1A
bridge location.

Synoptic Current Measurement

As mentioned earlier, synoptic current measurements were carried out by track-
ing drogues. Two field experiments were conducted, the first one during Jan. 10-11
and the second one in Jan. 30-31, 1990.

In the first experiment, 9 runs were made, all by airplane tracking. Each run
consisted of deploying 5 to 8 drogues simultaneously. The 4th run of the experiment
was, however, not completed due to malfunction of camera. In the second exper-
iments, airplane tracked only 5 runs owing to fog and a potential thunder storm
approaching the area. However, while in the absence of airplane, the drogues were
tracked from the beach using two fixed transit stations. The tidal current curves












SEBASTIRN INLET TIDE HISTORY


8 9 10 11 12 13 14 15 16 17 18 19
TIME (DRY) JRN. 1990











20 21 22 23 24 25 26 27 28 29 30 31
TIME (DRY) JRN. 1990

--- OFFSHORE
AT BRIDGE
--- NEAR RIVER
S, ,,t .


1 2 3 4 D 5
TIME (DRY)


6 7 8 9
FEB. 1990


10 11 12


Figure 16: Sebastian Inlet tide history; Jan.8-Feb.9, 1990.

















SEBRSTIAN INLET


COE LRB. UF


3




2
Uc
IFT/S)






0





N


8c E
(DEG)

S

W


6


3
TIDE
(FT)
0


-3

-6


1 5 10 15 20 25 30


+




S+
+ +
(B) CURRENT DIRECTION
+1

I 5 I I I 5 I I I I I2 i i i i I i i i i i
5 10 15 20 25 30


1 5 10 15 20 25 3

JAN. ,1990


Figure 17: Current and tide data collected at the offshore station.










SEBASTIAN INLET CURRENT/TIDE HISTORY
(AT BRIDGE)


- 5
LL

S 0


Z
UL

oL


~10~ I I I I I I I I J 3
I I I I I I I I I I


-10 I -3
8 9 10 11 12 13 111 15 16 17 18 19
TIME (DRY) JAN. 1990
10 3

2
5


0 0


S-5 -
-2

-10 I-i -3
20 21 22 23 24 25 26 27 28 29 30 31
TIME (DRY) JAN. 1990
10 3

CURRENT 2
- 5 TIDE


0 0
LU
cc V 1
aC -5
S-2

-10 I III I I I I-3
1 2 3 4 5 6 7 8 9 10 11 12
TIME (DRY) FEB. 1990


Figure 18: Current and tide histories at A1A bridge station.


3

2

LU_

0

-2

-2


'-


LU

I-


I-
U_

UJ
CD







































VELOCITY (FT/S)
AT EBB TIDE
(JAN.30-31,90)


100 200 300 400 500


SHORIZONTRL DISTANCE (FT)


Figure 19: Mean current measurement at the cross section under A1A bridge.


-5



-10



-15



-20









SEBASTIRN INLET CURRENT/DISCHRRGE HISTORY
(RT BRIDGE)
10 1200

-5 -600 a
LL '




0 I I I I I I I I -1200

8 9 10 11 12 13 11 15 16 17 18 19
TIME (DRY) JAN. 1990
10 1200


5 600 a
0











z vvvVVvvvvvvvvyy

-5- -600 L
0














-10 I I I I I I I I I -1200
20 21 22 23 2 25 26 27 28 29 30 31
TIME (DRY) JRN. 1990
10 1200
c -CURRENT
- 5 ---- DISCHRRGE 600


00

S-5 -600
u M
CC















-10 I I I I I I I I I I -1200
1 2 3 2 5 6 7 8 9 10 11 12
TIME (DRY) FEB. 1990

Figure 20: Current and discharge histories at A1A bridge station.
Fiue 0 Cret n dshrg isois tAI rdg tain








during these two deployment periods are given in Figure 21. On these curves, the
time and duration of each deployment are marked. It can be seen that in the first
experiment, (1/10 to 1/11) most of the deployment were in the ebb cycles whereas
in the second experiment (1/30 to 1/31) the bulk of the drogue tracking was during
the flood cycle.

The wave conditions during these two experiments were shown in Figures 22
and 23, respectively. During the first experiment, the waves were small and stable.
The significant wave height was only about 0.8 ft with mean modal wave period
around 8 sec. The wave direction on January 10th was from NE in the morning
but gradually shifted to easterly in the afternoon. On the 11th, the trend reversed,
shifting from easterly to northeasterly. Since the shoreline orientation is NW to SE,
a causal observer could mistakenly identify a wave from E or NEE as from SE since
the observer facing the ocean will have the sensation that the wave is approaching
from the right hand side as illustrated in Figure 24. In the second experiment, waves
were also reasonably stable but higher than the first experiment. Mean significant
wave height was about 2.6 ft with corresponding modal wave period of about 11 sec.
These were swell conditions with direction of approaching about 800 from the north,
or almost easterly wind. A detailed tabulation of wave and current conditions at
each deployment is given in Tables 2 and 3. The results of the synoptic current
measurements are given in Figures 25 to 28.



3 Fixed Bed Model Descriptions


3.1 Test Facility


The model study was carried out in the three-dimensional wave basin in the
Coastal and Oceanographic Engineering Laboratory at University of Florida. The
basin has a dimension of 160 ft x 110 ft by 2 ft high. On one end of the basin
is the snake-type wave generator. It consists of 80 independently controlled wave
paddles. The stroke, the phase angle and frequency of each paddle movement can
be varied to produce waves from up to 600 from parallel to the generator face, and
up to 1.5 sec wave periods. Wave height limitation depends on the water depth; up
to 0.4 ft can be achieved. A system made of pumps, weir gates and weir boxes was
developed to regulate the tidal current condition in the basin.










INLET CURRENT HISTORY


TIME (HOUR) JRN.10-11,1990


MEASURED
AT BRIDGE
4A 4
5

lA 5A


1


23


11 III1 I11111 1 11 I I1 1 1 ll!llfl l i I l ll
1 5 10 15 20 1 5 10 15 20


TIME (HOUR)


JRN.30-31,1990


Figure 21: Time and duration for drogue test studies.


SEBRSTIAN








INLET WAVE HISTORY


1 5 10 15 20 1 5 10 15 20
TIME (HOUR) JRN.10-11,1990


1 5 10 15 20 1 5 10 15 20
TIME (HOUR) JAN.10-11,1990











I 5 10 15 20 1 5Ill 10II IIIII1 1 III IIIIIII
1 5 10 15 20 1 5 10 15 20


TIME (HOUR)


JRN.10-11,1990


Figure 22: Offshore wave history; Jan.10-11, 1990.


3.0


2.0


Hs
(FT)
1.0


0.0


20


TH
(SEC)


SEBASTIAN








INLET WAVE HISTORY


1 5 10 15 20 1 5 10 15 20
TIME (HOUR) J-RN.30-31,1990


1 5 10 15 20 1 5 10 15 20
TIME (HOUR) JAN.30-31,1990











I I I I I I I I I I I I i l l i i l i i i L I II I I I I I I I I I I Il I I II
1 5 10 15 20 1 5 10 15 20


TIME (HOUR)


JRN.30-31,1990


Figure 23: Offshore wave history; Jan.30-31, 1990.


3.0


2.0


Hs
(FT)
1.0


Ii liii 1111111 lillililli gig iii iii iiiiiiiii liii


0.0


20


TM
(SEC)


SEBASTIAN




















































Figure 24: Wave approaching direction during the drogue test studies








30



















U1

Lu
C3


00
(3

X:
0

LL

lJ
Z
t")
z

a:








It-
(n
a--
D(
LU



a:
t










u-
Lld







C




I-
I-.









LU
Cr
C:






LLU




cc
I-
U)

C





u-
IU-
0


-2100 -1800 -1500 -1200 -900 -600 -300 0 300 600 900 1200 1500 1800 2100 -2100 -1800 -1500 -1200 -900 -600 -300 0 300 600 900 1200 1500 1800 2100

LONGSHORE DISTANCE FROM S. JETTY. FT) LONGSHORE DISTANCE FROM S. JETTY IFT)



Figure 25: Ebb current vectors droguee test by aerial photos), Jan.10, 1990.


3600


3300 IRUN-2) 11:31-11:59, JRN.10.1990

+ MARKER LOCATION
3000


2700


200 -


2100 +


1800 -


1500 /


1200


900 -


600 + +


300 I F/SEC

0 l I I I I

-2100 -1800 -1500 -1200 -900 -600 -300 0 300 600 900 1200 1500 1800 2100


3300 IRUN-5) 14:1I5-15;40, JAN. 10, 1990

+ MARKER LOCATION
3000


2700




2100 -


1800


1500 -


1200


900
+ ~~----
600 -. +


300 I FT/SEC
+

0 I I I I II


-2100 -1600 -1500 -1200 -900 -600 -300 0 300 600 900 1200 1500 1800 2100

(RUN-3) 13:17-13-57, JAN.10.1990

+ MARKER LOCATION







+ +






-, I


.4-


- I FT/SEC


+ + -I


I











3600 3600

3300 IRUN-6I 12:45-13: 18. JRN. 11, 1990 3300 IRUN-7) 13:30-14:24, JRN. I 1990
S30 + MRRKER LOCATION 0 + MRRKER LOCATION
3000f / 23000 -

200 2700 -

3 2400
2_+ + +
D 2100 + + 2100 +



S 15000 500 '

1200 120 -.



2900 9 00 -

+ 600 600 +
L.
U-
I F C + oo I Ft/SEC 4-
S 300 I F 300 I SEC

0 Ii I I I I I II I #
-2100 -1800 -1500 -1200 -900 -600 -300 0 300 600 900 1200 1500 1800 2100 -2100 -1800 -1500 -1200 -900 -600 -300 0 300 600 900 1200 1500 1800 2100

3300 (RUN-8) 16:02-16:25. JRN. 1 1990 3300 (RUN-9) 16:47-17:34, JRN. 1 1. 1990 .- '

S+ MRRAKER LOCATION + MRRKER LOCATION
3000 3000

S2700 2700 -

a:
Co 2100 2400 -
+ + + +
S --- + + + / 11
2100 + 00 -
LL 1 "" .......



T 1500 1500 -
fJ S..- .....-*






I-
2: 600 4 4 600 +


S30 0 I F T/SI C 30 0 I Fl /SEC ...... ... ... .... ... .. ... .

0 I I I I I I I I + I + 0I I I I I I I
-2100 -1800 -1500 -1200 -900 -600 -300 0 300 600 900 1200 1500 1800 2100 -2100 -1800 -1500 -1200 -900 -600 -300 0 300 600 900 1200 1500 1800 2100

LONGSHORE OISTRNCE FROM S. JETTY IFT) LONGSHORE DISTANCE FROM S. JETTY (FT)


Figure 26: Ebb current vectors (by aerial photos), Jan.11, 1990.











































-300


-2100 -1800 -1500 -1200 -900 -600 -300 0 300 600 900 1200 1500 1800 2100

LONGSHORE DISTANCE FROM S. JETTY (FT)


(RUN-4qA5A) 9:13-14:30, JAN.31,1990

+ MARKER LOCATION



+ +
+ +


+ g+


A
I/


I I


/SEC


'9

// /


S .... ....


I I I I I I


-2100 -1800 -1500 -1200 -900 -600 -300 0 300 600 900 1200 1500 1800 2100

LONGSHORE DISTANCE FROM S. JETTY (FT)


Figure 27: Flood current vectors droguee test by land transits), Jan.30-31, 1990.



33


(RUN-Il) 10:47-13:20, JRN.30,1990

+ MARKER LOCATION


II FT/S
!/





*+ 7

. .... ... + 1


SI I I II L I


-300


I


I I I I I I


I I
























,eo IRUN-II 1t330-I'iI0, JAN.30.1990
HIIAKER LOCIION


L000 .O S C F SJT,

m Ii





"+ I /




-hlre a.ooo .loo .*1o 0 .5oo -Ioo 0 o a Ioo 1 00 o* 00 iao too taoo 1100
LONGSHORE O1STANCE FROM S. JETT IFT)


)n IRtJN-21 15148-16i 1. JAN.30.1990
M* fRinER LOCATION


/ /



Doo F








11.0 0 00 .O20 .l.'<-00 .00- 02 .o 000 500 000 200 000 000 200

LONGSIHORE DISTANCE FROM S. JETIT tIFI


Io. IRUIN-I 10i53-11l'13, JAN.31.1990
HARDER LOCATION












.00 -. .

E DISTANCE FRO S. JETT IFT


-*i *o lloo -I100-I Io a -too -*00 *jo )* *o *oo (loo iioo r 1100
LOIGSHORE OISTRNCE FROM S. JETTT 1FT)


.*Loo -ioo ioo *iioo *Ioo s-oo .oo O 10 s oo I oo Io lIo 11ioo a In
LONGSHORE DISTANCE FROM S. JETTY IFTI


Figure 28: Composite current vectors (by aerial photos), Jan.30-31, 1990.


- OSoo -oo E D ISTANCE FRO -So. 1JETIo Io o i. o .- I
LOIGSIIHORE DISTANCE FROM S. JETII IFII










Table 2: Field Drogue Test From Aerial Photos (Jan.10-11,1990).

Run (#) Current* Wave Wave Wave
Date Time at Inlet Height Period Direction**
(ft/s) (ft) (sec) (degree)
(1) 10:34 -3.28 1.25 4.4 202
1/10/90 11:15
(2) 11:31 -3.64 1.21 4.6 202
1/10/90 12:40
(3) 13:17 -1.97 1.02 9.0 245
1/10/90 14:10
(5) 14:45 -0.33 0.98 9.1 252
1/10/90 16:30
(6) 12:45 -4.20 0.98 6.4 222
1/11/90 13:25
(7) 13:30 -4.49 0.95 9.0 241
1/11/90 15:30
(8) 16:02 -1.77 0.98 7.0 220
1/11/90 16:40
(9) 16:47 -0.88 0.98 6.4 206
1/11/90 17:55
+/- values indicate the flood/ebb tidal current;
**direction to where waves propagate.

3.2 Model Scale

The fixed bed model is undistorted so that wave geometry can be properly main-
tained. A length scale of 1 to 60 of model to prototype was chosen to accommodate
the area of interest within the confine of the basin. Figure 29 shows the area mod-
eled in the laboratory and the locations of the flow control devices and wave maker.
This roughly covers 2,500 ft downdrift (south) of the south jetty, 1,800 ft updrift
(north) of the jetty, 30 ft contour offshore and A1A bridge landward.

Similarity between model and prototype is based on Froude law which states


( ihi)m


where V is a characteristic velocity, L is a characteristic length and g is the grav-
itational acceleration. The subscripts m and p refer to model and prototype, re-
spectively. For a length scale ratio of 1:60, all other scales of pertinent engineering
quantity can be determined and are listed as follows:


V ),








































In
(V
0-




a
UJ
_J


o


I.
KyY










Table 3: Field Drogue Test From Aerial Photos (Jan.30-31,1990).


Run (#) Current* Wave Wave Wave
Date Time at Inlet Height Period Direction**
(ft/s) (ft) (sec) (degree)
(1A) *** 10:47 4.59 2.30 10.6 258
1/30/90 13:20
(1) 13:30 -2.69 2.46 11.6 256
1/30/90 15:30
(2)(3) 15:48 -3.94 2.53 11.6 256
1/30/90 17:30
(4A) 9:13 4.92 2.46 11.6 264
1/31/90 10:30
(4) 10:53 5.35 2.33 11.6 265
1/31/90 11:50
(5) 12:00 4.10 2.30 11.6 264
1/31/90 12:50
(5A) 13:37 -0.98 2.26 11.6 263
1/31/90 14:30
+/- values indicate the flood/ebb tidal current;
**direction to where waves propagate;
** droguess in (1A), (4A) and (5A) were traced by transits.

Length scale NL = Lm/Lp = 1/60
Cross-section scale, NA =N2 = 1/3600
Volume scale, Nv = N- = 1/216,000
Velocity scale, Nv = Vm/Vp =(NL)1/2 = 1/7.746
Time scale, NT = Vm/Vp = (NL)1/2 = 1/7.746
Discharge scale, NQ = NrNT = 1/27,885
Slope scale Ns = 1
Wave steepness Np = 1


3.3 Model Construction

Construction of the fixed-bed model was based on a template scheme that re-
sulted in a concrete bottom replica of the study area. The 1989 bathymetric map
of the inlet area, surveyed and prepared by Morgan and Eklund Inc. of Deerfield
Beach, FL., was used. Masonite templates were prepared and laid on the basin
floor. They were leveled in with reference to 1929 N.G.V.D.









The construction procedure consists of manually filling in and compacting sand
between templates. Concrete of about 1.5 inches thick was placed on top flush
with the templates. Figure 30 shows the construction of the model during concrete
placement. At the inlet section a smaller grid of templates is made to reproduce the
necessary curvature of boat channel. The concrete layer in the inlet was roughened
to simulate rock bottom. The model was then painted white to provide an aesthetic
quality as well as a clearer representation of the overall layout. Figure 31 shows the
completed model. A black-color grid system was painted on the floor to identify
positions of current and wave measurement. This grid system is shown in Figure 32.

The tidal current is controlled by a number of pairs of weir-gate system in the
model (see Figure 29). The flood flow is regulated by the discharge from a pair
of weir boxes located offshore near the wave paddle. The ebb flood, on the other
hand, is regulated by the discharge from the weir box installed behind the inlet.



3.4 Instrumentation


Discharge

The discharge which controls flow rate at the inlet is measured by notched
sharp-crested weirs installed at weir boxes. These weirs were calibrated to estab-
lish discharge-elevation curves by using conventional volumetric measurement as a
function of time.

Waves

Waves were measured by capacitance-type wave gages. The gages were statically
calibrated before and after each run. One wave gage was mounted permanently at
offshore station to measure input waves. Another wave gage was mounted on a
portable tripod to measure waves at predetermined stations marked on the floor.

Current

Current was measured by a miniature electrogenic current meter (0.5 inches in
diameter) manufactured by Marsh-Mcbirney Inc. It was also mounted on a portable
tripod.

Water Surface

Water surface elevation was measured by standard point gage mounted on tri-
pod.























































Figure 30: Construction of the fixed-bed model.























































Figure 31: Completion of the fixed-bed model.

























































Figure 32: Photography showing grid system on the model floor.


41









3.5 Model Calibration


In theory, in a combined current-wave model, both current and wave conditions
should be calibrated. In practice, wave calibration is not practical for a number of
reasons. First of all, field wave condition is hard to simulate accurately because it
is a fast time-varying phenomenon and it is often irregular in the field. Secondly,
the spatial variation is usually large. Calibration over multiple points requires the
deployment of many gages in the field. Thirdly, model adjustment, if required, is
also impossible to accomplish in a three dimensional situation. Therefore, current
calibration is the only viable means.

If the current conditions are simulated with reasonable accuracy, the corre-
sponding water surface elevation should also follow the scaling law correctly. Based
upon field measurement, the mean current velocity Vp and discharge Qp under A1A
bridge, and the water level differences AVp between the offshore and A1A bridge
stations for the maximal flood and ebb flows were found as follows:

Table 4: Vp, Qp and A~P measured in the field.

Tide Velocity Vp (ft/sec) Discharge Qp (yd3/sec) Aji (ft)
Flood 6.6 1040 1.0
Ebb 5.0 780 0.5

Based upon 1 to 60 length scale ratio, the required water level difference in
the model, (AT)t, corresponding to these conditions should be 0.2 and 0.1 inches,
respectively, for flood and ebb. The measured surface differences, (Aj)m, in the
model when the discharges were adjusted to the required flood (0.037 yd3/sec) and
ebb (0.028 yds/sec) values were 0.192 and 0.092 inches, respectively. Thus, the
difference between measured and required values was equal to 0.008 inches for both
flood and ebb cases. The relative errors, expressed by

e(%) = [At -Alm7/Ait x 100%

were 4 % and 8 %, respectively, for the flood and ebb cases. Thus, both the absolute
and relative errors are small. These results are summarized in Table 5.

Table 5: Errors of water level differences in the model.

Tide Ait (inch) AVI, (inch) |AYt AiT (inch) e
Flood 0.2 0.192 0.008 4 %
Ebb 0.1 0.092 0.008 8 %








4 Model Tests on Structural Improvement


4.1 Test Procedures


Six alternative structural configurations described in Section 1.4 were tested.
In each structural alternatives, a combination of current and wave conditions were
tested. These test conditions, totaled 88 cases, were summarized in Table 6. In
general, tidal current conditions included flood and ebb. In a few cases, slack water
condition was also added. The strength of the flood (ebb) current used in the test
was equivalent to 6.6 (5.0) ft/sec. As far as wave condition was concerned, the wave
period was kept constant at 8 sec. Two input deepwater wave heights, HD, of 1.64
ft (0.5 m) and 6.6 ft (2.0 m) were tested; the former represents the normal wave
condition and the latter the extreme or storm wave condition. Since wave direction
plays an important role in sediment transport as well as navigation, three directions
were tested; they were 0 (normal to shoreline), +100 (from NE) and -100 (from
SE).

The test procedures comprised of the following steps:


(a) Adjust the flow rate at weir boxes until the right discharge was first attained.
Currents were measured at the bridge cross section. Adjustment on the dis-
charge was made, if necessary, till the current at the control section reached
the specified values. The flow was then allowed to stabilize before proceed.

(b) Waves were generated by activating the wave generator.

(c) Wave and current data were then acquired from the predetermined stations
marked on the floor. Figure 33 shows the stations where waves and currents
were measured.

(d) Flow trajectories were monitored by video camera tracing the movement of
small floating drogues (2 inches in diameter) in each run.




4.2 Test Results


Detailed test results are presented in graphical forms in Appendix 2. The infor-
mation for each run contains the spatial distribution of wave heights and current
vectors. In this section, a synthesized description for each structural alternatives is
given.






















Table 6: Test conditions for the six structural alternatives.


Design Tide Wave conditions (TD=8 sec)
struct. (F, E calm E direction(0) NE direction(10) SE direction(-100)
type* or S)t sea HD:6.6' 1.64' HD:6.6' 1.64' HD:6.6' 1.64'
F 1 2 3 4 5 6 7
0 E 8 9 10 11 12 13 14
S 15 16 -
1 F 17 18 19 20 21 22 23
E 24 25 26 27 28 29 30
2 F 31 32 33 34 35 36 37
E 38 39 40 41 42 43 44
3 F 45 46 47 48 49 50 51
E 52 53 54 55 56 57 58
S 59 60 -
4 F 61 62 63 64 65 66 67
E 68 69 70 71 72 73 74
5 F 75 76 77 78 79 80 81
E 82 83 84 85 86 87 88


* Six testing plans:


0 for no structure; 1 for extending N jetty by 250 ft; 2 for extending S


jetty by 100 ft plus Plan 1; 3 for adding 50 ft spur structure at mid section of N jetty plus
Plan 2; 4 for extending N jetty by 500 ft and S jetty by 100 ft; 5 for excavating ebb shoal
from Plan 0.
t F stands for flood, E stands for ebb, S stands for slack tide.



















SCALE, I INCH 500 FEET
DEPTH CONTOUR IN FEET
E ONLT HAVES MEASURED
A ONLY CURRENT MEASURE
0 BOTH HA. AND CU. MEASURED


-10.00 -5.00
X


0.00 5.00 10.00
(100FT)


Figure 33: Waves and current measurement stations.


OFFSHORE
(D"


C)
0

(1)










C-
00
0_
I--
LL.







0
0













0-


-20.00


-20











-10










0



alif
AIA
HIHfWAT

20.00


-15.00


15.00
15.00


V
m I


I I .









4.2.1 Alternative "0"


Alternative "0" means existing condition which also serves as the reference con-
dition. In the subsequence discussions of other alternatives, they are often referred
to or compared with this alternative.

Wave Condition

Wave heights were measured at the predetermined stations as shown in Fig-
ure 33. It is evident that the most critical location is just seaward of the north
jetty on both sides of the boat channel. This is because the incoming waves when
approach the channel refract towards the shallow water on both sides. Because the
extensive ebb shoal on the south side, wave shoaling is also much more pronounced
here than the north side. Further south over the ebb shoal, the topography is such
that the waves wrap around the shoal due to diffraction, producing short-crested
waves while focusing behind the shoal. Because the waves are short-crested in the
region, the wave height distribution is very uneven spatially producing local highs
and lows. This condition is illustrated by the aerial photo shown in Figure 7. A
computer simulation shown in Figure 34 clearly defines the nature of the waves.
This wave focusing phenomenon was also reproduced in the laboratory (see top
photo in Figure 35). At the entrance of the jetty, waves shoal up rapidly over the
oblique cross-channel shoal. Once over the shoal, waves again are diverged toward
the banks on the two sides of the boat channel (see bottom photo in Figure 35).

In the laboratory model, the local wave conditions were found, at times, un-
stable. This was particularly the case under the combined large waves and strong
current condition. At a fixed location, often high waves and low waves were alter-
nately measured. This was probably due to the combined effects of basin oscillation
and wave reflection from beaches, structures and currents. It was, however, diffi-
cult to sort out the basin effect which is a source of contamination. In the results
reported herein both high and low values are given to indicate the range.

The laboratory results showed that waves were enhanced in region "A" delin-
eated in Figure 36, for all current conditions whether it is ebb, slack or flood. Wave
amplification is most pronounced when large waves met the ebb current head on.
Under this condition, incoming deepwater wave height could be more than doubled
in the southern portion of region A. Under flood condition, the waves were stretched
and flattened which led to lower amplification in the order of 1.5 times the incoming
waves. For low incoming waves, the amplification was also found to be lower.

In so far as the effect of wave direction is concerned, waves that approach straight
to the inlet at 0 approaching angle, in general, created the highest amplification.
The north jetty provided some shielding effect for waves from the north and the









Surface Wave Field
HD=6.6 ft, D=0,
TD=8 sec
Vbb at bridge= -4 ft/sec


Figure 34: Computer simulation of wave field during ebb.















































































Figure 35: Waves generated during the ebb cycle in the model.


I 1


let





-dadp-







OW
ir -9R M














SEBASTIAN INLET CONTOUR MAP 1989


Scale: 1 Inch = 800 feet
Depth Contour In feet


Region A: High Wave Amplification
Region B: Ebb Shoal Dominates the Wave Pattern
Region C: Sheltered Area, Waves Diverge to Banks


16.00


24.00


32.00


40.00


X (ft) x 100


Figure 36: Regions of different wave characteristics.


38


32.00-


24.001


x




>-


8.00




0.00





-8.00
-8.00


0.00


8.00
8.00


48.00


56.00


I I


---









ebb shoal offered a limited protection for waves from the south.


The wave conditions at Stations #6, 7, 8 and 14 are summarized in Table 7.
Stations # 7 and 8 are located along the existing main navigation path; #7 is at the
jetty entrance and #8 is half way between the north and south jetties. Stations #6
and 14 are located at the jetty entrance for alternative "1" and "4", respectively.

In region "B", where incident waves are strongly influenced by shoaling, diffrac-
tion and refraction owing to the presence of the shoal, waves tend to break over the
shoal under most circumstance except low waves during flood period. Therefore,
the measured nearshore waves (Stations #16, 23 and 27) were generally lower than
the incident waves except in the last case mentioned above where the wave heights
could double that of the incident waves. Also, as mentioned earlier, in this shallow
water zone behind the shoal, waves are short-crested, thus, the spatial distribution
of wave height was found to be uneven.

Inside the inlet, in region "C", behind the oblique shoal, waves diminished very
rapidly under all the conditions tested. By the time the waves reached the tip of
the south jetty, waves were generally reduced to less than one-half of their original
heights.

In summary, the existing wave environment can be characterized as follows:


(a) Wave activity is most vigorous just outside the north jetty entrance; waves that
reach to 12 ft can be expected under storm condition.

(b) The worst wave condition is under the combined condition of ebb current and
waves straight toward the inlet (approximately from east).

(c) In the vicinity of the entrance before reaching the oblique shoal, waves diminish
slightly but still large, around 9 ft, under storm condition.

(d) Once behind the entrance shoal, waves diminish very rapidly and fan out to-
wards the bank.

(e) The ebb shoal on the south side of inlet plays a dominant role on the wave
climate, causing complicated wave and current pattern.


Current Condition

Based upon the observed current pattern, one may conclude that the ebb current
is mainly shaped by the configuration of the jetty whereas the flood current is more
influenced by both the jetty configuration and ebb shoal.
















Table 7: Wave Height Amplification [Alternative Ho/Referenced HD].

0D (deg.) 00 +100 -100
HD (ft) 1.64 6.6 1.64 6.6 1.64 6.6
Ebb 1.23 1.80 1.64 1.74 2.10 1.79
Station #6 Ho/HL 0.28t 0.41 0.75 0.53 0.32 0.48
Flood 1.01 1.23 1.63 1.06 1.18 1.34
1.05 0.88 1.11
OD (deg.) 00 +100 -100
HD (ft) 1.64 6.6 1.64 6.6 1.64 6.6
Ebb 1.07 1.57 0.82 1.17 2.10 0.92
Station #7 Ho/HD 0.44t 0.29 0.53 0.89 -
Flood 1.57 1.54 1.33 1.27 0.78 0.93
0.69 0.73
OD (deg.) 00 +100 -100
HD (ft) 1.64 6.6 1.64 6.6 1.64 6.6
Ebb 1.39 1.34 0.99 1.03 2.59 1.21
Station #8 Ho/HD 0.39t 0.10 0.53 1.13 0.34
Flood 0.94 0.75 0.78 0.79 0.99 0.90
0.54 0.49 0.73
0D (deg.) 00 +100 -100
HD (ft) 1.64 6.6 1.64 6.6 1.64 6.6
Ebb 1.23t 1.64 1.25 1.85 1.38 1.69
Station #14 Ho/HD 0.31t 0.89 0.96 0.40 0.48
Flood 1.88 1.28 1.24 1.00 1.76 1.52
0.88 1.37
* Ho is the measured wave height of Alternative "0"; HD and OD are the referenced offshore
wave height and direction, respectively;
t The top and bottom values (if presents) represent maximum and minimum of relative
wave heights, respectively.








During ebb cycle, the current behaves like a jet carrying with it a rather concen-
trated seaward momentum. This jet when deflected by the curved north jetty directs
itself towards southeast, which gradually shaped up the present flood channel. A
clockwise vortex is formed on the south side behind the jet stream. The vortex is
weak for small waves but becomes better organized with increasing strength as the
waves become large. This is because waves will now break over the shoal converting
oscillatory wave motion into translator current. The current field associated with
this vortex is weaker than the flow in the channel but is an important factor in the
ebb shoal development. The direction of incident wave does not seem to have any
significant effect on the currents in the immediate vicinity or inside of the channel.
Figure 37 shows the ebb current patterns measured in the field and laboratory.

During the flood cycle, the current converges to the inlet like flow into a funnel.
Owing to the presence of the north jetty, the main flood channel is oriented slightly
toward the southeast following the curved configuration of the north jetty. Flows
are being prevented from entering the inlet directly from the north side. Marginal
flood channels were developed on the south side by cutting through the ebb shoal.
Thus, the flood flow is predominately from east-southeast. As a consequence, the
flood current tends to form an angle when entering the inlet which is oriented toward
east, instead of following the main channel as the ebb current does. A very strong
northwest oriented current component develops near the tip of the south jetty. This
local current is likely to carry sediment back into the channel and deposits them
on the bank inside the south jetty. Figure 38 shows the flood current patterns
measured in the field and laboratory.

The observed effects of waves on current can be summarized as follows:


(a) Waves under normal condition have very minor effect on the current in the
vicinity of the inlet.

(b) Under large wave condition, currents in the inlet tend to rotate more towards
the north, thus, result in stronger cross-channel current component under
flood condition.

(c) A clockwise gyre is created just outside the inlet, which coincides with the local
scouring hole for both ebb and flood conditions.


4.2.2 Alternative "1"


Alternative "1" extends the north jetty 250 ft. with a radius of approximately
900 ft. The principle effect of this extension is the reduction of wave height near the










3600

3300 DURING EBB, JRN.30,1990
+ MARKER LOCATION
3000

2700

2400
c ~--2'?
2100 / +

1800 +






00 I-
/oo, ,,/ \ i.









300 I FT/SEC.... ........ ..... ... .... ... .
+ + +
1200
-2100 -1800 -1500 -1200 -900 -600 -300 0 300 600 900 1200 1500 1800 2100

LONGSHORE DISTANCE FROM S. JETTY (FT)

3600

3300 MODEL SIMULATION (EH05)
+ MARKER LOCATION
3000

2700

2400
+ +
2100 + +

1800 .




1200 I /
1500 1\ ---': 3" ;"



900

600 + +

300 I FT/SEC ....... ......... ...................... .
-+ +4 +

-2100 -1800 -1500 -1200 -900 -600 -300 0 300 600 900 1200 1500 1800 2100

LONGSHORE DISTANCE FROM S. JETTY (FT)


Figure 37: Ebb current patterns measured in the field and laboratory.


I








































-2100 -1800 -1500 -1200 -900 -600 -300

LONGSHORE DISTANCE


2100

1800


0 300

FROM S.


600 900

JETTY


1200

(FT)


1500 1800 2100


-2100 -1800 -1500 -1200 -900 -600 -300

LONGSHORE DISTANCE


0 300 600 900

FROM S. JETTY (F


1200 1500 1800 2100


Figure 38: Flood current patterns measured in the field and laboratory.


DURING FLOOD, JAN.30-31,1990

+ MARKER LOCATION



+ +
,i + +.



I / .

..... / .. ,7 ...
-- F 7S--





-- I FT/SEC I+ +



II I tII I i i-
fl ,?/ + ^
^


MODEL SIMULATION (FH05)

+ MARKER LOCATION



+ +
++ +

II F
I I l I
I ll
..- --. I



//

.. +"... + f




I FT/SEC t

-- I --- 1 --- I --- I --- I --- I ---- --- I I I I I I










Table 8: Wave Height Ratio [Alternative "1" (Hi)/Alternative (Ho)].

Flood
OD (deg.) 0 100 -100 Ave.
HD (ft) 1.64 6.6 1.64 6.6 1.64 6.6
#6 0.60 0.77 0.79 0.86 1.10 0.82 0.82
HI/Ho #7 0.36 0.34 0.79 0.33 0.71 0.70 0.54
#8 0.36 0.85 0.87 0.46 0.73 0.99 0.71
Ebb
OD (deg.) 00 100 -100 Ave.
HD (ft) 1.64 6.6 1.64 6.6 1.64 6.6
#6 0.92 0.60 0.90 0.69 0.44 0.29 0.64
H1/Ho #7 0.74 0.49 0.39 0.44 0.33 0.33 0.45
#8 0.40 1.08 0.72 1.00 0.32 0.85 0.73
* H1/Ho is computed based on the averages of max. and min. wave heights shown in the
figures in Appendix 2.

existing inlet entrance (Stations #6, 7, and 8). Table 8 compares the wave height
ratios at these stations with and without the extension.

Under flood condition, this reduction ratio varies between 54-82%. The struc-
ture is more effective for ebb flow condition as these ratios drop to 45-73%. It is
also evident that the wave height ratios are the lowest at Station #7 which is now
located in the shadow zone behind the new jetty extension. Outside this region,
waves are not significantly affected by the extension. Waves measured just the north
side of the jetty were slightly higher than that of the original configuration owing
to, probably, the jetty reflection effect.

The flood current condition is not significantly affected by the extension. The
current at the new entrance location (#6) was found to be generally stronger be-
cause the flow cross section at this location is reduced. The absolute magnitude
being less than 1.64 ft/sec is, however, not that high. The current at the original
entrance location (#7), on the hand, is decreased somewhat. This is because the
flood current now curves around the new jetty will create a separation zone in this
vicinity. The entire flood current field was also being pushed towards the south
resulting in slight rotation of the current vectors towards the north when entering
the inlet. This means an increase in cross-channel current component.

The ebb current, in the presence of the new jetty is being directed more towards
the south. Near the entrance of the inlet, the current strength increases considerably
under the present condition. This is due to the combined effect of shallower water
and narrower cross section. The existing main flood channel is expected to shift








towards south to realign itself with the new ebb jet which is oriented towards south
of the existing jet. This adjustment will eventually create a new channel, reduce
the ebb current strength and push the ebb shoal further south. Figure 39, which
compares the vectorized ebb current patterns between alternatives "1" and "0"
cases (labeled by EH20M10S01 and EH20M10S00, respectively) under waves of 6.6
ft height and -10" approaching angle, illustrates this development.

The effects of waves on current are such:


(a) During flood, the current is not significantly affected under normal wave con-
dition (HD=1.64 ft).

(b) Under storm condition (HD=6.6 ft), flood current strength increases consider-
ably, particularly, when waves come from northeast meeting the flood current
head on. Strong wave-induced current was seen developed over the ebb shoal
(Figure 40).

(c) During the ebb cycle, the current strength around and inside the inlet is not
significantly affected by the waves. In the ebb shoal region, a weak circulation
is induced due to breaking waves. The magnitudes of the main ebb current
field are not affected.



4.2.3 Alternative "2"


This Alternative is the same as "1" plus 100 ft. south jetty extension at an angle
pointing towards southeast. Waves and current conditions in the vicinity of the
entrance are not affected by the addition of the south jetty. The flood current was
observed significantly reduced just inside the south jetty. This reduction in currents
could affect the local sediment transport but has no significance in navigation as
the surrounding water is very shallow.


4.2.4 Alternative "3"


This Alternative is the same as "1" with a short spur jetty on the north main
jetty. This Alternative was abandoned after a few trail to only find very minor
effect near the channel. It might have much pronounced effect on trapping sand on
the north side of the north jetty.


























































20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 1.00
X (100FT)

OEPIH CONTOUR IN FEET OFFSHORE
+ CURRENT MEnSUnED POSITION """
CRSE:EH20MIOSOO





-30 ............... .....


-20.00


LEGCTH SCALE. I IN.- 500 Fr.IN FIELD
VELOCITr SCALE, I IN.- I FT./S IN MODOEL
DEPTH CONTOUR IN FEET
CURRENr NEASUREO POSITION
CRSE:EH20MIOSO0





-30 ---.......----
.... .... ... .... ... .... ... .... ...


-15.00 -10.00 -5.00 0.00 5.00 10b.oo 15.00 20.00
X (100FT)


Figure 39: Comparison of

the laboratory.


Structure "1" and "0" ebb current vectors measured in


OFFSHORE



S1i








"`-
~''


-30







-20










-10









0



fin
HIGIIHfI
I
20.00






-30







-20










-10









0



ARI
HIGHHAT


































t-
LL.
00
0
CD0.
CD tCt





C0
CD


Figure 40: Structure "1" flood current vectors under the northeast storm waves.










Table 9: Wave Height Ratios of [Alternative "4" (H4)/Alternative "0" (Ho)].


Flood
OD (deg.) 0 100 -100 Ave.
HD (ft) 1.64 6.6 1.64 6.6 1.64 6.6
#6 0.49 0.33 0.4 0.48 0.30 0.69 0.45
H4/Ho #7 0.23 0.32 0.39 0.30 0.42 0.76 0.40
#8 0.36 0.66 0.94 0.50 0.42 0.60 0.58
#14 0.69 0.90 0.97 1.22 1.39 1.26 1.07
Ebb
OD (deg.) 00 100 -100 Ave.
HD (ft) 1.64 6.6 1.64 6.6 1.64 6.6
#6 0.5 0.34 0.36 0.16 0.26 0.20 0.30
H4/Ho #7 0.5 0.29 0.27 0.21 0.20 0.24 0.29
#8 0.59 0.29 0.22 0.27 0.30 0.34 0.34
#14 0.49 0.96 0.28 0.58 0.34 0.81 0.58


* H4/Ho is computed based
figures in Appendix 2.


on the averages of max. and min. wave heights shown in the


4.2.5 Alternative "4"


In this Alternative, the north jetty is extended 500 ft. from the original config-
uration and the south jetty is extended 100 ft. at in Alternative "2". With this
configuration, now, both stations #6 and #7 are inside the jetty and the entrance
is located further south at #14. Under this configuration, the existing channel is
further sheltered against waves from east and northeast.

Further reduction in wave activities inside the inlet at #6, #7 and #8 should
be expected. Table 9 summarizes the wave reduction ratios at selected stations in
the vicinity of the inlet.

Clearly, by comparing with Alternative "1" (250 ft north jetty extension), this
configuration achieves better wave reduction inside the jetty. The current strength
inside the channel and near the entrance does not change significantly for either
ebb or flood.

However, owing to the alignment of the jetty the entrance is now facing south,
the currents form a large angle to the channel axis as the flood water enters the
channel from east.

During the ebb cycle, the current inside the channel and at the entrance remains








strong, if not stronger than the existing conditions. The topography near the en-
trance will be altered in a short time as new flood channels begin to develop on the
south side. The existing ebb shoal would most definitely be built up further south.

Two new concerns should be addressed. One is the return current from the
south and the other is the cross wave at the entrance; both were observed in the
experiment. Apparently owing to the new channel alignment, the return flow from
the south toward the inlet is much better organized now than the existing condition.
This is because the main flow is further compressed towards the shoreline. The
induced eddy behind the jet, now being compressed, results in increased strength,
thus, stronger return flow towards the channel. This return flow is particularly
prominent during northeasters as can be seen in Figure 41. This strong return
flow is likely to transport sediment into the channel. The incoming waves are also
partially reflected from the ebb jet just outside the entrance creating a northward
current which is opposite to the main southward ebb jet. A strong shear flow zone
is, thus, created near the tip of the jetty. This condition is illustrated in Figure 42.

The other aspect is the cross wave outside the entrance. Since the entrance
is almost facing south and the predominant wave direction is from the east, the
incoming waves now meet the ebb current at a larger angle. This could create a
problem for navigation as one is faced with the choice of heading into the waves
by turning east exposing to a cross current or proceeding toward south with the
current and experiencing a beam sea.


4.2.6 Alternative "5"


In this alternative, the ebb shoal is partially removed. The jetty configuration
is the existing condition.

Table 10 summarizes the wave height amplification ratio at selected stations in
the vicinity of the entrance and inside the channel. Under flood condition, wave
heights reduce slightly at most stations except #14, which is really located outside
the main navigation channel. Under ebb condition, with the exception of #7 (at
the entrance), wave condition, on the average, does not change significantly. At #7,
waves experience an average of 40% increase. The most affected case is the normal
wave (1.64 ft) from east (00). Under this condition, waves at all four stations are
amplified with an average amplification ratio of 1.8. Wave measured at #7 has the
largest amplification ratio of 2.64 which translates into 4.3 ft when the incoming
wave height is 1.64 ft. With the exception of this case, the overall level of wave
intensity in this region remains essentially unchanged. However, in the nearshore
zone on the south side of the inlet, the wave intensity increases. This is expected
due to the removal of the shoal, thus, the shielding for this region.











































Figure 41: Structure "4" flood current vector field under the northeast storm waves.














LENGTH SCALEi I IN.. 500 FT. IN FIELD
VELOCITY SCALEi I IN.- I FT./S IN HODEL
DEPTH CONTrOU IN FEET
+ CURRENT MEASURED POSITION
CASE: EH20DOOSO4


OFFSHORE
.. ...-


o,'"


c)






ru





L('

0

0-
F-
U-




O
0.












o
o
in


e-
UC)

en


-20.00


+ .. ...............
"- + --'-t"" "...







S +


... +... .... ..... .

...............


15.00
15.00


-10









0



nin
AIR
HIGHWAY
20.00
20.00


Figure 42: Structure "4" ebb current vector field under the east storm waves.


- o ..... ..




S ............................. I ................ -- -.


I I I I I I
-15.00 -10.00 -5.00 0.00 5.00 10.00
X (1OOFT)


U


,...- .. .. ,


IBII
.










Table 10: Wave Height Ratios of [Alternative "5" (Hs)/Alternative "0" (Ho)].


Flood
0D (deg.) 00 100 -100 Ave.
HD (ft) 1.64 6.6 1.64 6.6 1.64 6.6
#6 0.84 0.65 1.03 0.40 0.86 0.76
Hs/Ho #7 0.78 0.94 0.80 0.87 0.56 0.93 0.81
#8 0.95 1.32 0.82 1.03 0.51 1.13 0.96
#14 1.39 1.30 1.06 1.66 1.15 0.84 1.23
Ebb
0D (deg.) 00 100 -100 Ave.
HD (ft) 1.64 6.6 1.64 6.6 1.64 6.6
#6 1.90 0.97 1.04 0.87 0.50 0.83 1.02
Hs/Ho #7 2.64 1.17 2.04 0.97 0.66 0.91 1.40
#8 1.46 1.02 1.11 0.56 0.40 0.76 0.89
#14 1.23 1.00 1.12 1.00 0.83 1.08 1.04


* Hs/Ho is computed based
figures in Appendix 2.


on the averages of max. and min. wave heights shown in the


The currents inside the inlet and near the entrance remain largely unaffected.
Over the region where the shoal has been removed the current magnitude during
flood diminishes slightly owing to the increase in water depth. The ebb current,
instead of being deflected by the shoal to form a return flow, now spreads over the
region and fans out towards south. This situation is illustrated in Figures 43 and
44. The eddy behind the jet on the south side which is rather prominent in the
existing condition is now much weaker and less organized. Waves now break much
closer to shore than before. As a consequence, the wave-induced current is also
weaker and much closer to the shoreline. Since this wave-induced current no longer
feeds into the tidal current, the flood flow becomes less strong compared with the
existing condition under the same wave environment (Figure 45). Similarly, under
ebb condition, the wave-induced current is less likely to feed the vortex behind the
jet. This situation is shown in Figure 46.



5 Summary and Recommendations


The purpose of the fixed bed model study is to examine various structural alter-
natives for the improvement of inlet navigation. The major findings are summarized
here.

























t t


LENGTH SCALE, 1 IN.- 500 FT.IM FIELD
VELOCItT SCALE, I IN.. I FT.IS IN MODEL
DEPTH CONTOUR IN FEET OFFSHORE ...--*....
S 4+ CURRENT MEASURED POSITION
0 CASE:FHOODOOS05 ...
L- -30
S............... *
S -3 .............................

C) -30 ..-'" '-.


t
.............
..............................
-20 .......... ..
4- :


o .

0 -.............. t .........



.....................................................................


RIA
HIGHWAY


-10







0


-'1s.00 -10o.oo 0.o 00o
X$ (100FT)


5.00 .oo0 15.o00 20.00


OEPFH CONTOUR IN FEET
+ CURRENT HESURED PO SITIO
CASE: FHOOOOSO0


-20 ..........

............/ '


t


/ / A/

r .


-15.00 -10.00 -5.00 0.00
tL7 (1OOFT)


-10


............ ....... ..........





HIGHHWAT
f-






V )HI


5.00


10.00 15.00 20.00


Figure 43: Comparison of Structure "5" and "0" flood current vectors (calm sea)

measured in the laboratory.


20.00


OFFSHORE



...................... -....



-10
-to ....... ............


0 .......................................-


o
1-
-20.00
-20.00


I


...---.....

....................................................


%






















































-15.00 -10.00 -5.00 0.00 5.00
X (100FT)


10.00 15.00 20.00


N CONTOUR IN FEETI OFFSHORE
CURRENT NERSURED POSITION
ASE:EHOOOOOSOO



.,'.
.,-""%


-15.00 -10.00 -5.00
X

Comparison of Structure


0.00 5.00
(100FT)

"5" and "0" ebb


-30






-20









-10








0



RIA
HIGHWAY


1b.oo 15.00 20.00


current vectors (calm sea)


measured in the laboratory.


LENGTH SCALE, I I H.. 500 FT.MI FIELD
VELOCIIT SCALER I IN. I I T./S IN MODEL
OEPTH CONTOUR IN FEET
+* CURRENr NMfSUREO POSITION
CASE:EHOOOOOS05


-30


AIR
HIGHIWAY


-20.00


0O
+
CF


O:


-20.00


Figure 44:





OFFSHORE .....


..........................


-- ---- ----


-~~-~~--~


t-


















































00 -15.00 -10.00 -5.o 0.00
(100FI

DOETH CONTOUR IN FEET OFFSHORE
+ CURRENT NHESURED POSITION
CASE:FH20HIOS0




- 30 ..... .........







-20 .
t


-10 ........ ......... ...-..



0 ......... .......... ................ .............


+ t t
....... ............ .. t





-0 ....................

.../. .............
0 .............................................. .......... .

+ i





HIGHHRT


5.00 10.00 15.00 20





-30









o"" \
... ..' ...












-10


i.00


................... 0


Figure 45: Comparison of Structure "5" and "0" flood current vectors (under storm

waves) measured in the laboratory.

66


0--


LENGTH SCALE. I IN.. SOO FT.IN FIELD
VELOCITT SCALE, I In.. I FT./S IN MOOEL
DEPTH CONTOUR IN FEET
+ CURRENT MNESURED POSITION
CASE:FH20MIOS05




-30 ......................" "


20.


. s #


OFFSHORE
...-." "". """.*...



o,' .-.


i














L[EHGH SCAtLE I IN.- 500 FT.IN FIELD
VELOCITY SCALE, I IN.. I FT./S IN OOEL.
ODPIH CONTOUR IN FEET OFFSHORE ..... .... .
+ CURRENT IMESURED POSITION
CASE: EH20MIOS05 ..

.. ''............... .. -



-30 "




2 "' +20

.. ........................ ;





........... ....

............... .................
0 ..................................... .o0


........ ....
S................. .





AIA
Hr\ ^n


-15.00 -10.00 -5.00 0.00
X (100FT)


5.00 10.00 5.00o 20.00


OFFSHORE .
$-- "


~~I~~ I I I


-15.00 -10.00 -5.00 0.00
X (100FT)


-30






-20









-10








0



AIA
HIGH WT


5.00


10.00 15.00 20.00


Figure 46: Comparison of Structure

waves) measured in the laboratory.


"5" and "0" ebb current vectors (under storm


20.00 .


OEP1H CONTOUR IN FEET
+ CURRENT HERSUREO POSITION
CASE:EH20M 0500


-30..
....................................


o I


-20.00


I I I


V-








5.1 The Model Tests


The fixed model is undistorted at a scale of 1:60 of model to prototype. This
roughly covers 2,500 ft down drift (south) of the south jetty, 1,800 ft up drift of the
jetty, 30 ft contour offshore and A1A bridge landward.

Six structural configurations at or near inlet entrance, as shown in Figure 8,
were tested. These alternatives were:

0 Existing jetty configuration.
1 North jetty extended 250 ft with a radius of approximately 900 ft.
2 Plan #1 plus 100 ft south jetty extension.
3 Plan #2 plus 50 ft spur jetty on the north jetty.
4 North jetty extended 500 ft and south jetty extended 100 ft.
5 Existing jetty plus partial removal of ebb shoal.

In each alternative, a combination of current/wave conditions were tested. A
total of 88 cases were listed. The current strengths used in the model study were 6.6
ft/sec prototype equivalent under flood and 5 ft/sec prototype equivalent under ebb.
Wave conditions tested included storm wave condition and normal wave condition
with various directions.


5.2 The Findings

Alternative "0"

Under existing structural configuration, an oblique shoal exists which
extends from the south jetty to the north jetty.
Outside the shoal, a zone of "considerable" wave enhancement can be
detected.
Behind the oblique shoal, inside the channel, waves diminish rapidly and
fan off towards the inner banks.
Wave conditions on the south side are dominated by the ebb shoal effects.
Unless the incoming waves are very small, they tend to break over the
shoal and focus behind it, creating short-crested waves and confused
current pattern.
The worst wave conditions near the inlet appear to be associated with
waves from east which approach the inlet head on or at a slight negative
angle, i.e., between E and SEE. Waves amplification is most pronounced
under ebb condition. At the entrance, waves as high as 11.5 to 13.8 ft
prototype equivalent were measured.









The ebb current behaves like a jet and is mainly shaped by the config-
uration of the jetty. The flood current converges towards the inlet from
the SE quadrangle cutting through the ebb shoal. The current pattern
is influenced by both the jetty and the shoal.
Inside the inlet, flood current is generally stronger than the ebb current
(field evidence).
Flood current is very strong at the tip of the south jetty.

Alternative "1"

Under this configuration, a wave reduction along the main navigation
channel can be expected. Under ebb condition a wave height reduction
of 25-50% is achieved whereas under flood condition is between 18-45%.
Current conditions are only slightly affected by the new structure. The
ebb jet is being pushed toward south with little change in strength. The
flood current strength increases under strong northeaster waves.

Alternative "2" and "3"

Both Alternatives have little effect on the flow condition along the main
navigation route. The extension of the south jetty in Alternative "2"
eliminates the strong flood current component near the tip of the existing
south jetty.

Alternative "4"

When compared with Alternative "1", more effective wave height re-
duction is attained along the existing navigation channel; about 50%
reduction under flood and 70% under ebb.
However, the new entrance is now located at the fringe of the existing
ebb shoal where wave activity is strong, creating a new problem.
Return flow along the shoreline towards the inlet becomes stronger.
Under storm wave condition (particularly north), a rather strong north-
ward flow is developed just off the entrance of the inlet. This flow joins
with the southerly-directed ebb current creating a strong shear flow re-
gion.

Alternative "5"

With the exception of one case-normal wave condition (1.64 ft) with
0 wave angle-the wave conditions along the navigation route are not
adversely affected. Under a number of situations, the wave heights are
actually reduced. Under the worst condition cited above, wave height at
the inlet entrance is amplified by a factor of 2.64 which translates into
4.3 ft prototype wave height for an input wave of 1.64 ft.


I








In the nearshore zone on the south side of the inlet, waves under most
conditions are larger than the existing condition. Stronger longshore
current is expected.


5.3 Recommendations


For navigational improvement, Alternative "1" appears to be the most sensible
among the six Alternatives tested. This configuration probably should be chosen
as the basis for moveable test. It is, however, premature to conclude that this
Alternative is the optimum configuration. A number of issues should be examined,
among them:


(a) The effect of sand tight the now porous north jetty.

(b) The nature and cause of the oblique shoal at the channel entrance and the
effect of removing this shoal.

(c) The optimize configuration in terms of sand transfers and downdrift effect.

(d) Quantitative analysis of navigation improvement, i.e., such as the increase of
navigable days due to this improvement.



References

[1] Law of Florida, Chapter 12259.

[2] Mehta, A.J., Wm.D. Adams, and C.P. Jones, 1976. "Sebastian Inlet Glossary
of Inlets, Report #3", Coastal and Oceanographic Engineering Laboratory, Uni-
versity of Florida. COEL-76-011.

[3] Coastal Technology Corporation, Florida, 1988. "Sebastian Inlet District Com-
prehensive Management Plan".










Table 10: Wave Height Ratios of [Alternative "5" (Hs)/Alternative "0" (Ho)].


Flood
0D (deg.) 00 100 -100 Ave.
HD (ft) 1.64 6.6 1.64 6.6 1.64 6.6
#6 0.84 0.65 1.03 0.40 0.86 0.76
Hs/Ho #7 0.78 0.94 0.80 0.87 0.56 0.93 0.81
#8 0.95 1.32 0.82 1.03 0.51 1.13 0.96
#14 1.39 1.30 1.06 1.66 1.15 0.84 1.23
Ebb
0D (deg.) 00 100 -100 Ave.
HD (ft) 1.64 6.6 1.64 6.6 1.64 6.6
#6 1.90 0.97 1.04 0.87 0.50 0.83 1.02
Hs/Ho #7 2.64 1.17 2.04 0.97 0.66 0.91 1.40
#8 1.46 1.02 1.11 0.56 0.40 0.76 0.89
#14 1.23 1.00 1.12 1.00 0.83 1.08 1.04


* Hs/Ho is computed based
figures in Appendix 2.


on the averages of max. and min. wave heights shown in the


The currents inside the inlet and near the entrance remain largely unaffected.
Over the region where the shoal has been removed the current magnitude during
flood diminishes slightly owing to the increase in water depth. The ebb current,
instead of being deflected by the shoal to form a return flow, now spreads over the
region and fans out towards south. This situation is illustrated in Figures 43 and
44. The eddy behind the jet on the south side which is rather prominent in the
existing condition is now much weaker and less organized. Waves now break much
closer to shore than before. As a consequence, the wave-induced current is also
weaker and much closer to the shoreline. Since this wave-induced current no longer
feeds into the tidal current, the flood flow becomes less strong compared with the
existing condition under the same wave environment (Figure 45). Similarly, under
ebb condition, the wave-induced current is less likely to feed the vortex behind the
jet. This situation is shown in Figure 46.



5 Summary and Recommendations


The purpose of the fixed bed model study is to examine various structural alter-
natives for the improvement of inlet navigation. The major findings are summarized
here.








In the nearshore zone on the south side of the inlet, waves under most
conditions are larger than the existing condition. Stronger longshore
current is expected.


5.3 Recommendations


For navigational improvement, Alternative "1" appears to be the most sensible
among the six Alternatives tested. This configuration probably should be chosen
as the basis for moveable test. It is, however, premature to conclude that this
Alternative is the optimum configuration. A number of issues should be examined,
among them:


(a) The effect of sand tight the now porous north jetty.

(b) The nature and cause of the oblique shoal at the channel entrance and the
effect of removing this shoal.

(c) The optimize configuration in terms of sand transfers and downdrift effect.

(d) Quantitative analysis of navigation improvement, i.e., such as the increase of
navigable days due to this improvement.



References

[1] Law of Florida, Chapter 12259.

[2] Mehta, A.J., Wm.D. Adams, and C.P. Jones, 1976. "Sebastian Inlet Glossary
of Inlets, Report #3", Coastal and Oceanographic Engineering Laboratory, Uni-
versity of Florida. COEL-76-011.

[3] Coastal Technology Corporation, Florida, 1988. "Sebastian Inlet District Com-
prehensive Management Plan".


















APPENDICES








A Wave Statistics, Vero Beach (87, 88, 89)


Month (87)
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Annual

Month (88)
Jan
Feb
May
Jun
Jul
Annual

Month (89)
May
Aug
Sep
Oct
Nov
Dec
Annual


Mean H,(ft)


2.59
2.69
3.08
1.94
2.56
1.25
1.12
1.48
1.51
3.44
3.31
2.20
2.30


(1.18)*
(0.92)
(1.08)
(0.66)
(0.82)
(0.56)
(0.56)
(0.56)
(0.49)
(1.05)
(1.12)
(0.92)
(0.88)


Mean H,(ft)
2.82 (0.59)*
2.23 (0.88)
1.67 (0.66)
1.61 (0.85)
1.15 (0.79)
1.54 (0.66)

Mean H,(ft)
0.20 (0.06)
1.84 (0.88)
2.95 (1.08)
2.69 (1.18)
2.66 (0.85)
2.66 (0.95)
1.94 (0.85)


Max. H,(ft)
6.50 [ 1/ 6]
5.28 [2/ 5]
6.46 [3/ 7]
3.48 [4/27]
4.30 [5/10]
3.08 [6/ 7]
2.76 [7/20]
3.18 [8/14]
3.18 [9/ 6]
6.20 [10/12]
7.45 [11/ 2]
4.53 [12/ 8]
7.45 [11/ 2]

Max. H,(ft)
4.56[ 1/ 7]t
4.59 [ 2/ 6]
3.31 [5/ 2]
2.98[ 6/13]
3.67 [ 7/ 6]
4.59[ 2/ 6]

Max. H,(ft)
0.33[ 5/ 2]
6.04 [8/20]
5.51 [9/10]
6.10 [10/10]
4.89 [11/30]
4.92 [12/23]
6.10 [10/10]


Mean Tm(sec)
9.84 (3.01)*
9.45 (2.90)
9.74 (3.06)
10.25 (2.83)
8.22 (2.33)
7.78 (2.56)
8.08 (2.13)
8.04 (2.30)
8.65 (2.88)
8.36 (2.07)
8.39 (2.03)
8.72 (3.42)
8.80 (2.64)

Mean Tm(sec)
7.54 (2.90)*
7.21 (2.06)
8.13 (2.23)
7.53 (2.41)
7.31 (1.56)
7.54 (2.26)

Mean Tm(sec)
6.89 (1.20)
8.64 (2.38)
11.43 (3.14)
8.14 (2.26)
8.49 (2.66)
9.50 (3.48)
8.93 (2.67)


* Values in parentheses indicate the standard deviation.
t Values in brackets indicate the date.








B Test Results for Alternatives 0, 1, 4 and 5


This appendix summarized the model test results in figures. The results will be
shown here for Alternatives "0", "1", "4" and "5. The results for Alternatives "2"
and "3" are different from those for "1" only at small areas near south jetty and near
the outer mid section of north jetty and, therefore, are not shown in the appendix.
The results for all six testing structural alternatives are available in 5.25" floppy
diskettes at the Department of Coastal and Oceanographic Engineering, University
of Florida.

Two figures that summarize the measured wave and current information are
generated for each test case. The first figure shows the wave height amplication
factors relative to wave height measured at the offshore station. If two values are
given at a station, the top and bottom ones represent the maximum and minimum
of relative wave heights, respectively. The second figure shows the current vectors
measured at pre-selected stations.

The individual case is identified by 10-charater label. The first character is of
either E, F or S, which are corresponding to ebb, flood or slack tide, respectively.
The 2nd to 4th characters are either HOO, H05 or H20, which are corresponding to
wave heights of 0 ft, 1.64 ft (0.5 m) or 6.6 ft (2 m), respectively. The 5th to 7th
characters are of either DOO, D10 or M10, which are corresponding to wave directions
from 00 (E), 10 (NE) or -100 (SE) relative to normal-shore direction. The last three
characters are of either SOO, S01, S02, S03, S04, or S05, which are corresponding to
structural alternatives between "0" and "5". For example, EH20M10SO1 labels the
case of Alternative "1" during ebb tide with waves of height 6.6 ft coming from -100
(SE) direction.














LENGTH SCALE, I IN.- 500 FT.IN FIELD
DEPTH CONTOUR IN FEET
UPPER VALUEHaxH/HO. LONER VILUEHMIN/H0
+ WRVEHEICHT MERSUREO POSITION
CRSE:EHO5000SOO


-30 ....... .................................."...






+1.11

.......... .. ."
..... .. .+ .1


+ .... .
-20 0a... 0
0,20 / 1.20
1.21 +0..1






.-.---.......- -
.. 0.00

++0.3






/ i 4! ...... ......
+ .


-20


S......... ...
....................... ..............


-10










0




AIR
HIGH RAT


I. I I I I .I
-20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00
X (100FT)






o

0
LENGTH SCALE, I IN.- 500 FT.IN FIELD
VELOCITl SCALE I 1I. I. FT.IS IN MODEL
OEPTH CONTOUR IN FEET OFFSHORE
S+ CURRENT NEASUREO POSITION ...
o CASE:EHO5000SOO
o -30



a
0 -30





S-20 ...... '-20








o -10 -
0- -to ........--- ;.



0.........................--
0 ............................................

Si ................................ ...................................






AHIGHW
HlIBWAT
::> ____-------------------------- II H~


-20.00 -15.00 -10.00 -5.00 0.00 5
X (100FT)

B-2


.00 10.00 15.00 20.00


w0-(111


OFI


SHORE


-30


'= I


t














LENCGH SCALEs I IN. 500S FT.IN FIELD
OEPTH CONTOUR IN FEET
UPPER VYLUEIIMXII/O. LOMER VRLUEIHMNI/HO
+ MIYEHEIGHT MEASURED POSITION
CASE:EH050 1000





-30................


lO lc ..**
OFFSO--.
OFrSnORE .....""


+..H
.....-"......

.- . .. ... .. .,-, '

+ +0 .+ "

-... . .. ... . ; 6"1 i + '." ". +

.. ............
/+O .- .. . *-.. ... . + 0 -

S............................ .. ...

0 o.. .....-.. ,- ,:.
; ... "- +. l .... +0.5 IJ


AIA
HIGHWAT


II I
-20.00 -15.00 -10.00 -5.00 0.00 5.00.00 00 15.00 20.00
X (100FT)







0 --____________________________________________________


LENGTH SCALE, I IN. 500 FT.IN FIELD
VELOCItI SCLESI I IN.- I FT./S IN N00EL
DEPTH CONTOUR IN FEET
+ CURRENT MEASURED POSITION
CASE:EHO501OSOO


OFFSHORE .



-30


S .: I AIR
HIGHWAT


-s. -'o. -.oo I I
-15.00 -10.00 -5.00 0.00 5.00
X (100FT)
B-3


10.00 15.00 20.00
10.00 15.00 20.00


-20.00


=I


..................................................""















LENGIN SCALE, IN.. 500 FT.IX FIELD
OEPTH CONTOUR IN FEET
UPPER VALUEHHKX/HO. LOUER VALUEMMIN/HO
+ WuEHEICGHT MrESUREO POSITION
CASE:EH05MI0S00


OFFSHORE .. ""*.
.r.s-a'"


1.01 l.jl
+O.0 +m3 ,..
+0.17


.. .. .. \.

...-2.......... : -0
0 ... 1.11 ..l




+.-1 01. + S.!. ". .. .- +',.
-. .1.3. ..3e ..i. .. .. .,.
/0..7 +i+l"
/,+ .l ..0 -+9


+ A ... "-.... .................-." .
4.28 ......... + --




. .


AIa
HIGHWAT


-20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00
X (100FT)







0_


LENCTH SCALE, I I N.* S00 FT.I FIELD
VELOCITY SCALE, I IN.* I FT./S IN NOOEL
OEPTM COrNOUR IN FEET
+ CURRENT WEISUREO POSITION
CASE:EH05M1OS00


FFSHOHE ..--.....
0 ..o.O*" *"--....



'* ~-30


\ : I AI
HIGHRAT


-'15.00 -0.00 -5.00 0.00
X (100FT)

B-2


5.00 1b.00 15.00 20.00


-20.00


I '


...........................


...................................................."" "


/


''













LECNGT SCALEi I IN.- S00 FT. IN FtLD
DEPTH CONTOUR IN FEET
UPPER VRLUEIHKIN/HO. LOUWR VALUEiHlnIN/HO
+ W VEHEIGHT CMESUREO POSITION
CASE:EH05000SO1


-30


-30 ... .- ,





t.2





.-. .........."... ........ : 1

..... ..... +0,2

-10 .................-- + .


......... .... ...1"'.10
1.0- ---" I. I0l.



i i+ :*01
+;:i! +O*S'


-20


-10









0



Ali
- HIGHWAY


j I I 1 I
-20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00
X (100FT)





0
0
c)


LENGTH SCALE I IN.- S00 FT.IN FIELD
VELOCITT SCALEi I IN.- I FT./S IN MODEL
OEPTH CONTOUR IN FEET
+ CURRENT MEASURED POSITION
CASE:EH05000SOI





-30 .......... ..........


-20 ........


-20.00 -15.00 -10.00 -5.00
X


OFFSHORE



-30

...... ....... ...... ....





/. .. ''.-20











-to











t 'AIA


HIGHWAY


0.00 5.00 10.00 15.00
(100FT)

B-5


20.00


0


_


w


........ ............ ....,..
--'"'"'-.....,..


OFFSHORE


................-.%..














LENGIN SCALE, I IN.- 500 FT.IN FIELD
ODETN CONTOUR IN FEET
UPPER VALUEIHMalI/HO. LOUtR VrLUEHNIN/HO
+ MRVEHEIGHf MEASURED POSITION
CASE:EH05DIOS01


er.0. @1 cm". ..
..- '-....
OFFSHORE ...''" "'*..
-30


-20


0 6.51 U.,10 a.a
+ !.. +O.H


-20 -............. .



C) .... .......... .............. -to
,0 1
.. . . ...... ". .. . . .





















-20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00
,o, O
o i

( -1 ............... .






















o


LENGTH SCALE, I IN.- S00 FT.IN FIELO
VELOCITY SCALEs I IN.- I FT./S IN MOOEL
OEPTN CONTOUR IN FECT
+ CURRENT HEISURED POSITION
CASE:EH05010S0I


OFFSHORE


e .'


-20











-10









S0



AIR
HIGHHAT


-15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00
X (100FT)

B-6


-10 ......


0
CD
1_


r


-20.00


;;





. . . .. o.. ..










0
O

LECNTH SCALE, I IN.- S00 FT.IN FIELD
ODPTH CONTOUR IN FEET
UPPER VALUEUHHII x/HO. LOMER VAfLUEsHNIN/HO C........
c + WUVEHElCHt MEASURED POSITION
0 CFSE:EHO5M10S1O OFFSHORE
.' o-30



0
o -30

D-20



0- *. I.<*;
.-

.-......... .. o.-.. .. .0 \
.. ............. .-
0 ...... .*.. T..


D +. O...N--* TF '.** -10


CD -t0



'U '
: --... ... .------ ----................ .0 .--*- o-
... I .... .... .. ... ..










0 ---===- HIGHMAT
0 ... .. .. .... ........,-...... .... ... ....
o j" .....H*W.......H............. H










-20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00
X (100FT)






0
0

..H SC.LE, I 1. ... 700 fT.N FI EL
HELOC1TT SCALE, I IN.. I P7./S 1II OOEL
D C. .....OU ..... EET FF......SHORE
+ CURRENT HENSUR O I ...*. '
S CflSE:EHOSMIOSOI .... "
in ...--' D'* -30
S30........... ..............................................................................















0-
c
00 AIA
0C3 HIGHWAY






























-0. .00....00..........
or












-0 ......0-- -' ........





0 0 ... . . . . . . . .. "
..... . ,





L. E SCALE, I .IN.I SO MI F







0- HIGHl"T

-20o. 00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00
X (100FT)

B-7














LENGTH SCALE, t IN.- $00 FT.IN FIELO
OEPTH CONTOUR IN FEET
UPPER VALUEHMaR/MO. LOVER VALUEHMIN/HO
utavEHEIGHT MEASURED POSITION
CASE:EHO500OSO0






-30 .... ... ""


OFFSHORE
O/ 3 "C*..

,.*"n.
orrsno,


+0.00 +1tCI I.II
S +0.$4



+o*
++.30


-0 ..............................
/ 0. +0 + 0. 5**

0 +, ...



+0 "Pi ... +... ......


-20











-1Tn


1..1


-- -* -:5" +*.s
......... .


AIA
HIGHWAY


-20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 -20.00
X (100FT)









LENGTH SCALE I IN.* 500 FT.IN FIELD
VCLOCIT SCALE. I IN.- I FT.IS IN RO0EL
OEPTH CONrOUR IN FEET OFFSHORE .-- ..
0 + CURRENT -ESUREO POSITION
SCRSE:EH05000SO4
- .... ..... "" "'- -30




o -30 ........
c -30


.5 +


...** -... -20











-Ia


. ...... .







................................ 0




HIGHIAT


5.00


ib.oo 15.00 20.00


B-8


Ir-


-20.00


-'s.oo00 -o.oo -5.oo .o00
X (100FT)













O
0
nI
LENGTH SCALE I IN.. 500 FT.IN FIELD
DO THr CONTOUR IN FEET
UPPER VALUElnHX/,HO. LONER VALUEMNNIN/HO n..... .
u+ VEHEIGHN r ERSURED POSItiON "
o CASE:EHO0SDIOS04 OFFSHORE
n- ..''" -30




o -30
0-


Co -

C .... ..... ..
0o .. .,


-20 "


o ......... ... ". -10
+- -1 ............. ;


S........... ... ..------....... ... +,.,







o




X (100FT)










LENGTH SCALE I IN.- 500 FT.IN FIELD
YELOCITT SCALE I IN.- I FT./S IN MODEL
DEPTH CONTOUR IN FEET OFFSHORE ..---....
S + CURRENT MEASURED POSITION
S CASE:EHO 5010SO ..

Sn_ -30




-30

S..--.. ... -0







-20.00 -5.00 -.... 00 0.00 15.00 20.00
X . .FT
o


























0 SCR. I I... ....................
..L ..IT. SC.I .. i t .... I .0..S ..... .































w %. . ... .... .. ..
o HIGHWAY



i A .







X (100FT)

B-9
B-9









0
0

LENGCT SCALE I IN. 500 FT.IN FIELD
DEPTH CONTOUR IN FEET
UPPER ALUEn HHAI/HO. LOWER VALUEHNIN/HO ....
0 + NavEHEICHF MEASURE POSITION
0 CASE:EHO5M 10S04 OFFSHORE
0- -30




o-

S. -...... -20








H- 0
U-

0
0 U, ,


000 5.00 10"00""5.00 -20.00

.*.......*" /.... -10.. .

I -... .... '. / '; '








1X (100FT1
SLCIT "CL IN. I T. In ODEL
", -I

-o -. .




+ .. .. ... ..-------- ** +.. 0





0 ,, -o-..o- ...-"o-,---- ....................---------- O

-20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00
X (100FT)









VELOCITY SCBLEs I IN.- I FT./S IIN mOVEL
OEPTH CONrOUR IN FEET OFFSHORE
+ CURRENT MEASUREO POSITION N ...-""" ED.... .
o CASE:EHOSMIOS04 ....... "".... ...
S-30

o 0oO ...*.....................'.



o o





I0
20 ..".................
S -.... ... -
-0 ........ ... .
to1 ..........








.. .......... ..............


S............................................
o i '











9 -. ... .....................




o .
.-............. - Ain
Co HIGHWAY

-20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00
X (100FT)

B-10










0
0
o
LENGTH SCALE I IN.- 500 FT. I FIELD
OEPrM CONTOUR IN FEET
UPPER VALUEHNRX/n O. LOWER V.LUElsMIN/HO
S + UOEHEIGHT MEASURED POSITION o .
o CFSE: EH05DOOS0S o0r sOR
....*. -30.



o -30
o -
rU
-20



0








I-I
S... ..........



+ 2.00 +0.00
-20 m* + -10


.... .. .. .
X 10 + 0. F
o +. -10
o -10 ........ ............. +. ......




+ .......:-.....-........
+0 ................ ......
0 ........................................... :





o


-20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00
X (100FT)





o
0

LENGTH SCILE, I IN.- 500 FT.IN FIELD
tELOCIET SCLE. I I N. I FT./S IN ROtEL
DEPTH CONTOUR In FEET OFFSHORE .......
0 + CURRENI MEASURED POSITION
C CASE:EH05DOOS05 ...





o -30 ................
o-

-20
I-
iLL


. .- ...................... r
-20 *'-- -i


S0..... ...... 1
0L t o . . . . . . .. .. . -.. .
S. .......... .... ;



9 / 1. .-.. .- .

o A I



C- H IGHWAYI'
0 ------------------------------------- HIGH-flT




-h0.00 -15.00 -'10.00 5.00 0.00 5.00 10.00 5t.00 2b.oo

X (HOOFT)


B-11
/P
~~ I i0












B-li














LENGTH SCALE, I IN.- 500 FT.IN FIELD
OEPTH CON0OUR IN FEET
UPPER VlLUEIHAlX/HO. LOuER YVLUEiHMIN/HO
MRH"EMICHT MEASURED POSITION
CASE:EH05010S05






-30 ...
0 .......................................... ..."


_we.G.a.cn .o-"".....*..
S..-0." a-. C
OFFSHORE

-30


-20


+ .96 +.* q + .70
2.9
% + O .1l
... ..... ; .
0 ................ .. T "


......... ....... +01 *"


-10 .0.......... .o .
.*- 0. 92
0I.I o..a



0 ................................... ............
S. ........... '
.. .. ..,: .............-
I **



\ \0l


.... ......................

............


.. l.o +...l
."...... + I; 1) !l


-10










0



AIR
HIGHWAT


-o.oo -'.oo -io.oo .I o o ..
-20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00
X (10OFT)





o
0
oS____


ASE:EHO5010505




........................................ *... '"' .


LENGTH SCALE. I IIN. S00 FT.IN FIELD
VELOCITT SCALEs I IN.- I FT./I IN nODEL
DEPTH CONTOUR IN FEET
+ CURRENT MEASURED POSITION


C,


-30


-10


-10 ............


L I AIR
HIGHMAT


7 -- 7


-15.00 -10.00 -5.00
X


0.00 5.00
(100FT)

B-12


10.00 15.00 20.00


-20.00


= I


1


OFFSHORE



''5





-Zo















LENCGH SCALE I IN.- SOO FT.IN FIELD
OfEPT CONTOUR IN FEET
UPPER VYLUEIHIAX/HO. LOMER VALUEHMIM/HO
* IRVENEIGHI MEASUREDD POSITION
CASE:EHOSI10SS0


S 0. 1CO E'" ...
.8 *....- -..
OFFSORE ..0''' ''-..


N.M O.iT
+4.Sl +Fie h.N
+.0.39
t. 1
....... .......... .... 1.a +o..

-20 .



......... ...

-10 ......... . +1.0


I AIA
O HIGHWAT

-20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00
X (100FT)






o

.


LENGTH SCALEr I IN.- SO FT.IN FIELD
VELOCITY SCALE I IN.. I FT./S IN MODEL
OEP(H CONIOUR II FEET
+ CURRENT MEASURED POSITION
CASE:EH05MIOS05






0


OE


OFFSHORE .--...
(.


-30


-15.00 -10.00 -5.00 0.00


-15.00 -10.00 -5.00 0.00
X (100FT)

B-13


AIA
HIGHWAY


5.00 10.00 15.00 20.00


-20.00


m


............................-...


................................................. ... -. "' "


r















LECNTH SCALE, I IN.. S00 FT.IH FIELD
OEPTf CONTOUR IN FEET
UPPER VaLUEIHnRl/NO. LONER VflUEMMIN/HO
.+ uNEHEIGHT MEASURED POSITION
CASE:EH20000S00


CFSHo .3 C..
OFFSHORE


+,.57

.o" +l s2
.../ .. +"-0 .


..... ... .. I..I.


0 H IGHWAI

-20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00
X (100FT)







0
c
mI


LEGINC SCOLEL I I. I. 00 FT.IN FIELD
rELOCITT SCALE I I.I FT./S I NIOOEL
OEFPI CONTOUR II FEET
CURRENT MEISUREI POSITION
CASE:EH20000SO0






-30 ...........
........ ... .... ... .... ... .... ...


.o... -.......... .


-15.00 -10.00 -5.00 0.00
X (100FT)

B-14


5.00 10.00


15.00 2b.00


-20.00


S I AIA
HIGHWAY


~II


E I m m


................................... ............. ''


-30














LENGTH SCALES I IN.- S00 FT.IN FIELD
OEPTH CONTOUR IN FEET
UPPER VaLUEHMSX/HO. LOVER VALUEHNIN/HO ....
+ tIMVEMELCHr MIESURED POSITION
CASE: EH20010500 OFFSHORE






0


1.01 t.6
+1.I +,U6 I.|
+1.10


-20 .....***" 1.1 3 .
S .nl +o.r


-10 ....... ..
4, 31.31 1.10
+Ms .............*

1 .. .........




;.. .......


.............



-........ +..


AIA
HIGHWAY


SI II 11
-20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00
X (100FT)








c_


LENGTH SCALE, I IN.* 500 FT.IN FIELD
rELOCITT SCALE I IIN. I FTJ.S In M00EL
DEPTH CONTOUR IN FEET
+ CURRENT MEASURED POSITION
CR3E: EH200IOSO0


OFFSHORE ..--....



....-' '' -30


-10.00 -5.00 0.00
X (100FT)

B-15


5.00 10.00 15.00


-30


-20











-I0










0



AIR
HIGHHAT

20.00
20.00


-20.00 -15.00


;-_


'


I


I


. ...


r












LEGCrH SCALEs I IN. S00 FT.IN FIELD
DEPTI CONTOUR IN FEET
urPER VLUEsHMRxf/HO. LOMER VALUEHHIH/MO
* uAVEHEIGHT MEASURED POSITION
CASE:EH20M 1000


OFFSHORE


................


.. . . .. . :
..... .
+ l. I.I1
+ .i ...... .

-20 ........ .3 .

. . ; 1 .

-10 .....Z l..... +.' 0.
+o.31+0.o








1 ;15


-30


............. -......- '.
,l:#.-+-m +o.a5


S 1 21 ,+0.1
......... .. 2 .


AIR
HIGHWAT


-20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00
X (100FT)





0
0.,


II I
-15.00 -10.00 -5.00 0.00
X (10OFT)

B-16


5.00 10.00 15.00 20.00


LENGTH SCALE I IN.. 500 FT. I FIELD
VELOCITr SCALEi I IN.- I FT./S IN MODEL
DEPT CONTOUR IN FEET OFFSHORE ..----
+ CURRENT MERSUROE POSITlO
CASE:EH20M IOS00" -3







..... .. 3 0

0 ................................... .
- 3 0 .. .0







............ "^"I \
-10

-10 .............. ..





o...................................... ..

..- ........




..........................--------------------------------------
AIR
HIGHWtAY


O

-2


0.00


... ... .. ... ... .. ... .. ... ... .. ... .. --... '




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